She tweeted: "Boris Johnson has served our country and his constituency with distinction.
"He led world in supporting Ukraine, got Brexit done, and was our most electorally successful prime minister since Margaret Thatcher."
The background to Johnson's resignation - in 150 words
UK Parliament / PACopyright: UK Parliament / PA
Here's what's happened ahead of Boris Johnson dramatically resigning as an MP this evening.
Johnson was accused of misleading Parliament over parties held in Downing Street while the UK was under Covid restrictions during the pandemic.
During a hearing in March, he said he had misled Parliament over Partygate - but insisted he'd not done that deliberately.
Johnson was in a combative mood for the hearing and said the gatherings were "essential" work events which he believed obeyed the guidelines.
The former prime minister was given the findings of the MP-led investigation on Thursday. A "warning letter" from the committee set out the criticisms it intended to make and evidence supporting them.
If the committee finds he misled Parliament, it could have recommended his suspension from the House of Commons for 10 days or more, possibly leading to a recall vote and a potential by-election in his west London seat.
Johnson gave no notice to government whips
Ione Wells
Political correspondent
I understand Boris Johnson did not tell the Tory Party
whips he was resigning - which Nadine Dorries said she did when she quit earlier today.
'You literally owe him your seat': Johnson loyalists sound off
Ione Wells
Political correspondent
Some Boris Johnson loyalists elected in 2019 are not happy with tonight’s developments.
Johnson's resignation tonight has unleashed familiar Tory factions into the open again.
Another unhappy Tory, Brendan Clarke-Smith, tweets: "Tonight we saw the end result of a parliamentary witch-hunt which would put a banana republic to shame."
If you'd thought we'd seen the back of Tory civil war, tonight may have reopened that can of worms.
This post has been edited, as initially the last line was incorrectly attributed to Brendan Clarke-Smith.
Privileges Committee is target of Johnson's ire
Rob Corp
Live reporter
If you were going to do a word cloud based on Johnson's statement announcing he's quitting Parliament, Committee would be the one which stood out right at the centre.
It's clear the Privileges Committee are firmly in his sights - and at whose door the former prime minister is putting the blame for today's decision to resign as an MP.
If you need a reminder, the committee has been investigating whether he misled MPs over parties in Downing Street while Covid restrictions were in place.
This committee has a Conservative majority, and its membership and remit was voted on and endorsed by the House of Commons.
According to Johnson, the committee are "determined to use the proceedings against me to drive me out of Parliament", and have not produced any evidence he lied to MPs. He insists that in their "heart of hearts" they know he didn't lie, but have "wilfully chosen to ignore the truth".
All eyes are now on members of the Privileges Committee and its chair - veteran Labour MP Harriet Harman - to have their say in the face of these strident allegations made by the former prime minister.
Analysis
Johnson's resignation problematic for Tories struggling in polls
Leila Nathoo
Political correspondent
Following Boris
Johnson’s hugely explosive resignation, will there be a ripple effect across the Conservative Party?
We’ve already seen
Nadine Dorries resign today, forcing a by-election in her Mid Bedfordshire
constituency, and now we have another by-election in Johnson’s seat of Uxbridge
and South Ruislip.
This is clearly
problematic for a party struggling in the polls, and in the next few hours or
days it will be interesting to see what sort of ripple effect it has among
Boris Johnson’s supporters within the party.
Patel and Clarke not planning on resigning
Chris Mason
Political editor
There are a lot of rumours flying about - and we are not
in the business of rumours.
But I do check them out.
So are Dame Priti Patel and Sir Simon Clarke about to
resign too?
I have been in touch with both.
They both say no.
Johnson delivered on promises to residents - local Tory chair
We've just had some reaction from Boris Johnson's local Conservative association chairman, who says the former PM "has delivered on his promises to local residents".
Richard Mills says: "Contrary to external perception, his commitment to the constituency over the last eight years has been outstanding."
The Uxbridge and South Ruislip Conservative Association chair also praises Johnson for being the "driving force" behind a new Hillingdon Hospital as well as "protecting" Uxbridge police station.
Johnson jumped before he was pushed - SNP
UK ParliamentCopyright: UK Parliament
The SNP's deputy Westminster leader, Mhairi Black, says Johnson "jumped before he was pushed".
"No one in Scotland will be sorry to see the back of him but he has also underlined the weakness of Rishi Sunak, who has no authority over the bitterly divided Tory Party," says the MP for Paisley and Renfrewshire South.
Public sick of Tory soap opera - Labour
UK ParliamentCopyright: UK Parliament
We've just had some reaction from Labour, with the party's Deputy Leader Angela Rayner saying the British public is "sick to the back teeth of this never-ending Tory soap opera played out at their expense".
"After 13 years of Conservative chaos, enough is enough," she says.
She adds that it is time to "turn the page" with a Labour government "focused on the people's priorities".
Tories prefer local candidate in Dorries' seat - source
The close ally of Boris Johnson told TalkTV "something significant" had happened to change her mind but wouldn't give any further details.
That's led to speculation that she could have stood down to let Johnson stand in her much safer seat of Mid Bedfordshire, which has a majority of 24,664.
However, a Conservative party headquarters (CCHQ) source suggests to our political editor Chris Mason the party would prefer a "local" candidate for Mid Bedfordshire.
"The clear implication is they wouldn’t regard west London as ‘local'," he adds.
Johnson's current seat is Uxbridge and South Ruislip in west London, where he has a majority of 7,210.
BBC News streaming live now
A reminder, you can watch live rolling coverage at the top of this page - just click the big play button.
Analysis
Boris Johnson is leaving Parliament... for now
Chris Mason
Political editor
Boris Johnson is a regular deliverer of political
asteroids. Tonight, another one crashes in.
Not only is Boris Johnson giving up as an MP - triggering
a by election in a marginal seat.
He is doing so in an explosive manner - taking a direct
pot shot at Prime Minister Rishi Sunak as he does so.
Hours after stepping off a plane from Washington in which Sunak transparently wasn’t talking about a free trade agreement with the US (he was never going to be), Johnson says he should have been.
He claims the Commons Privileges Committee is a "kangaroo court".
And he is rallying the Brexit troops in suggesting his demise
is driven by a motivation to overturn the result of the EU referendum.
Oh, and anyone thinking Boris Johnson is about to retreat
into obscurity, note how his statement ends.
He is leaving Parliament "for now".
Boris Johnson's statement in full
Boris Johnson's statement in which he sets out why he is quitting Parliament and rails against the investigation into him clocks in at just over 1,000 words.
We're currently picking out the key bits on this page, but you can read his statement here in full.
I did not lie - Johnson
We're still picking through Boris Johnson's incredibly long resignation statement.
Taking aim at the Privileges Committee, who are investigating whether he misled MPs over Partygate, the former prime minister said: "I did not lie, and I believe that in their hearts the committee know it."
"They know perfectly well that when I spoke in the Commons I was saying what I believed sincerely to be true and what I had been briefed to say, like any other minister," he said.
Johnson said he corrected the record as soon as possible, and said committee members "know that".
Of course we're only getting Johnson's side of the story at the moment - we're chasing reaction from MPs and will bring you their response as soon as we get it.
Johnson had received Partygate report findings
Johnson’s
resignation comes the day after he received the findings of the Privileges
Committee, the MP-led investigation into whether he misled Parliament
over gatherings at No 10 Downing Street during the Covid lockdowns.
In evidence given
in March, Johnson admitted misleading Parliament, but denied doing it on purpose.
As we reported yesterday, Johnson was sent a “warning letter” by the committee, detailing the
criticisms it intended to make of him, as well as any evidence it had.
He was given two
weeks to reply to the letter.
Lib Dems react with just two words: Good riddance
Reacting to the news of Boris Johnson's resignation, Liberal Democrat deputy leader Daisy Cooper says simply: "Good riddance."
Johnson resignation triggers by-election
Boris Johnson's resignation triggers a by-election in his west London seat of Uxbridge and South Ruislip.
He has a majority of 7,210, with Labour coming second in the 2019 general election.
Labour had hoped a strong performance at the next general election could turn the seat red - but now it looks like they will get a crack at taking the constituency sooner than that.
Analysis
Johnson goes nuclear
Iain Watson
Political correspondent
Boris Johnson goes as an MP and goes nuclear.
He and Nadine Dorries are giving Rishi Sunak unwelcome by-elections and in his statement he suggests that the Conservatives have lost their mojo and abandoned key policies from tax to housing.
Johnson quits hours after rewarding key allies with honours
Getty ImagesCopyright: Getty Images
Boris Johnson’s resignation comes only hours after he gave
some of his closest allies – including Priti Patel and Jacob Rees-Mogg – peerages
in his honour’s list.
The long-awaited list, approved nine months after Johnson
resigned as prime minister, included 38 honours and seven peerages.
Among the big names were Leader of the Commons Jacob Rees-Mogg, who was knighted, and former Home Secretary Priti Patel, who was made a dame.
Live Reporting
Edited by Jamie Whitehead
All times stated are UK
Get involved
Johnson's legacy will stand test of time - Patel
More messages of praise for Boris Johnson, this time from one of his loyal supporters Priti Patel.
The former home secretary, who earlier in the day was made a dame in the former PM's resignation honours list, described Johnson as a "political titan whose legacy will stand the test of time".
She tweeted: "Boris Johnson has served our country and his constituency with distinction.
"He led world in supporting Ukraine, got Brexit done, and was our most electorally successful prime minister since Margaret Thatcher."
The background to Johnson's resignation - in 150 words
Here's what's happened ahead of Boris Johnson dramatically resigning as an MP this evening.
Johnson was accused of misleading Parliament over parties held in Downing Street while the UK was under Covid restrictions during the pandemic.
During a hearing in March, he said he had misled Parliament over Partygate - but insisted he'd not done that deliberately.
Johnson was in a combative mood for the hearing and said the gatherings were "essential" work events which he believed obeyed the guidelines.
The former prime minister was given the findings of the MP-led investigation on Thursday. A "warning letter" from the committee set out the criticisms it intended to make and evidence supporting them.
If the committee finds he misled Parliament, it could have recommended his suspension from the House of Commons for 10 days or more, possibly leading to a recall vote and a potential by-election in his west London seat.
Johnson gave no notice to government whips
Ione Wells
Political correspondent
I understand Boris Johnson did not tell the Tory Party whips he was resigning - which Nadine Dorries said she did when she quit earlier today.
'You literally owe him your seat': Johnson loyalists sound off
Ione Wells
Political correspondent
Some Boris Johnson loyalists elected in 2019 are not happy with tonight’s developments.
Workington MP Mark Jenkinson has taken aim at Christian Wakeford - the Labour MP who defected from the Tories amid the fallout over Covid rule-breaking parties.
"You literally owe your seat to him," he writes.
Johnson's resignation tonight has unleashed familiar Tory factions into the open again.
Another unhappy Tory, Brendan Clarke-Smith, tweets: "Tonight we saw the end result of a parliamentary witch-hunt which would put a banana republic to shame."
If you'd thought we'd seen the back of Tory civil war, tonight may have reopened that can of worms.
This post has been edited, as initially the last line was incorrectly attributed to Brendan Clarke-Smith.
Privileges Committee is target of Johnson's ire
Rob Corp
Live reporter
If you were going to do a word cloud based on Johnson's statement announcing he's quitting Parliament, Committee would be the one which stood out right at the centre.
It's clear the Privileges Committee are firmly in his sights - and at whose door the former prime minister is putting the blame for today's decision to resign as an MP.
If you need a reminder, the committee has been investigating whether he misled MPs over parties in Downing Street while Covid restrictions were in place.
This committee has a Conservative majority, and its membership and remit was voted on and endorsed by the House of Commons.
According to Johnson, the committee are "determined to use the proceedings against me to drive me out of Parliament", and have not produced any evidence he lied to MPs. He insists that in their "heart of hearts" they know he didn't lie, but have "wilfully chosen to ignore the truth".
All eyes are now on members of the Privileges Committee and its chair - veteran Labour MP Harriet Harman - to have their say in the face of these strident allegations made by the former prime minister.
Johnson's resignation problematic for Tories struggling in polls
Leila Nathoo
Political correspondent
Following Boris Johnson’s hugely explosive resignation, will there be a ripple effect across the Conservative Party?
We’ve already seen Nadine Dorries resign today, forcing a by-election in her Mid Bedfordshire constituency, and now we have another by-election in Johnson’s seat of Uxbridge and South Ruislip.
This is clearly problematic for a party struggling in the polls, and in the next few hours or days it will be interesting to see what sort of ripple effect it has among Boris Johnson’s supporters within the party.
Patel and Clarke not planning on resigning
Chris Mason
Political editor
There are a lot of rumours flying about - and we are not in the business of rumours.
But I do check them out.
So are Dame Priti Patel and Sir Simon Clarke about to resign too?
I have been in touch with both.
They both say no.
Johnson delivered on promises to residents - local Tory chair
We've just had some reaction from Boris Johnson's local Conservative association chairman, who says the former PM "has delivered on his promises to local residents".
Richard Mills says: "Contrary to external perception, his commitment to the constituency over the last eight years has been outstanding."
The Uxbridge and South Ruislip Conservative Association chair also praises Johnson for being the "driving force" behind a new Hillingdon Hospital as well as "protecting" Uxbridge police station.
Johnson jumped before he was pushed - SNP
The SNP's deputy Westminster leader, Mhairi Black, says Johnson "jumped before he was pushed".
"No one in Scotland will be sorry to see the back of him but he has also underlined the weakness of Rishi Sunak, who has no authority over the bitterly divided Tory Party," says the MP for Paisley and Renfrewshire South.
Public sick of Tory soap opera - Labour
We've just had some reaction from Labour, with the party's Deputy Leader Angela Rayner saying the British public is "sick to the back teeth of this never-ending Tory soap opera played out at their expense".
"After 13 years of Conservative chaos, enough is enough," she says.
She adds that it is time to "turn the page" with a Labour government "focused on the people's priorities".
Tories prefer local candidate in Dorries' seat - source
Just a few hours ago former minister Nadine Dorries also announced she was standing down as a Conservative MP with immediate effect.
The close ally of Boris Johnson told TalkTV "something significant" had happened to change her mind but wouldn't give any further details.
That's led to speculation that she could have stood down to let Johnson stand in her much safer seat of Mid Bedfordshire, which has a majority of 24,664.
However, a Conservative party headquarters (CCHQ) source suggests to our political editor Chris Mason the party would prefer a "local" candidate for Mid Bedfordshire.
"The clear implication is they wouldn’t regard west London as ‘local'," he adds.
Johnson's current seat is Uxbridge and South Ruislip in west London, where he has a majority of 7,210.
BBC News streaming live now
A reminder, you can watch live rolling coverage at the top of this page - just click the big play button.
Boris Johnson is leaving Parliament... for now
Chris Mason
Political editor
Boris Johnson is a regular deliverer of political asteroids. Tonight, another one crashes in.
Not only is Boris Johnson giving up as an MP - triggering a by election in a marginal seat.
He is doing so in an explosive manner - taking a direct pot shot at Prime Minister Rishi Sunak as he does so.
Hours after stepping off a plane from Washington in which Sunak transparently wasn’t talking about a free trade agreement with the US (he was never going to be), Johnson says he should have been.
He claims the Commons Privileges Committee is a "kangaroo court".
And he is rallying the Brexit troops in suggesting his demise is driven by a motivation to overturn the result of the EU referendum.
Oh, and anyone thinking Boris Johnson is about to retreat into obscurity, note how his statement ends.
He is leaving Parliament "for now".
Boris Johnson's statement in full
Boris Johnson's statement in which he sets out why he is quitting Parliament and rails against the investigation into him clocks in at just over 1,000 words.
We're currently picking out the key bits on this page, but you can read his statement here in full.
I did not lie - Johnson
We're still picking through Boris Johnson's incredibly long resignation statement.
Taking aim at the Privileges Committee, who are investigating whether he misled MPs over Partygate, the former prime minister said: "I did not lie, and I believe that in their hearts the committee know it."
"They know perfectly well that when I spoke in the Commons I was saying what I believed sincerely to be true and what I had been briefed to say, like any other minister," he said.
Johnson said he corrected the record as soon as possible, and said committee members "know that".
Of course we're only getting Johnson's side of the story at the moment - we're chasing reaction from MPs and will bring you their response as soon as we get it.
Johnson had received Partygate report findings
Johnson’s resignation comes the day after he received the findings of the Privileges Committee, the MP-led investigation into whether he misled Parliament over gatherings at No 10 Downing Street during the Covid lockdowns.
In evidence given in March, Johnson admitted misleading Parliament, but denied doing it on purpose.
As we reported yesterday, Johnson was sent a “warning letter” by the committee, detailing the criticisms it intended to make of him, as well as any evidence it had.
He was given two weeks to reply to the letter.
Lib Dems react with just two words: Good riddance
Reacting to the news of Boris Johnson's resignation, Liberal Democrat deputy leader Daisy Cooper says simply: "Good riddance."
Johnson resignation triggers by-election
Boris Johnson's resignation triggers a by-election in his west London seat of Uxbridge and South Ruislip.
He has a majority of 7,210, with Labour coming second in the 2019 general election.
Labour had hoped a strong performance at the next general election could turn the seat red - but now it looks like they will get a crack at taking the constituency sooner than that.
Johnson goes nuclear
Iain Watson
Political correspondent
Boris Johnson goes as an MP and goes nuclear.
He and Nadine Dorries are giving Rishi Sunak unwelcome by-elections and in his statement he suggests that the Conservatives have lost their mojo and abandoned key policies from tax to housing.
Johnson quits hours after rewarding key allies with honours
Boris Johnson’s resignation comes only hours after he gave some of his closest allies – including Priti Patel and Jacob Rees-Mogg – peerages in his honour’s list.
The long-awaited list, approved nine months after Johnson resigned as prime minister, included 38 honours and seven peerages.
Among the big names were Leader of the Commons Jacob Rees-Mogg, who was knighted, and former Home Secretary Priti Patel, who was made a dame.
Read more here.