Labour Party MP David Lammy has co-ordinated some of the campaigning around the Windrush generation.

After Ms Rudd resigned, he said the campaign was "not just about political scalps" and her resignation "must not detract from the fact that this crisis was a direct result of the hostile environment policy".

Yesterday a letter from Mr Lammy and more than 200 other MPs called for government promises to Windrush migrants to be written in to law. It said promises the government made over compensation, housing or legal rights should be enshrined in law "without delay".

Image source, PA

The loss of her home secretary has presented the Prime Minister with numerous problems, writes the BBC's political editor Laura Kuenssberg.

Image source, Other

Replying to Ms Rudd's resignation letter, Theresa May wrote that she was "very sorry" to see her leave the Home Office and she should "take great pride" in what she had achieved.

Full text: Amber Rudd's resignation letter and Theresa May's response

Shadow Home Secretary Diane Abbott welcomed Ms Rudd's resignation.

She told 5 live's Stephen Nolan: "It was the right thing to do."

She added that the Labour Party was "determined to see justice for the Windrush generation, so in that sense it is not over."

Patrick Vernon started a petition just over two weeks ago, calling for an amnesty for anyone arrived as a minor in the UK between 1948 to 1971.

He told BBC Radio 5 Live's Stephen Nolan: "Despite Amber Rudd leaving her post, the government still has a big job to do."

"I wasn't looking for a resignation... what the families want is their right as British citizens."

George Parker, the Financial Times' political editor, tweets that Amber Rudd's friends admit that "she should have known".

Danny Shaw
BBC Home Affairs Correspondent

"With responsibility for immigration, counter-terrorism and policing, the job of home secretary is one of the toughest in government.

During one period under Labour, there were six home secretaries in eight years.

But Amber Rudd's job was made doubly difficult because she was following Theresa May, who'd survived in the post for more than six years and had set in train a series of plans and objectives that Ms Rudd was expected to stick to, even if she disagreed with them.

The former energy secretary was unable to put her stamp on any significant policy during her 21 months at the Home Office; much of her time was spent fire-fighting - dealing with the implications of Brexit, the rise in violent crime and last year's terror attacks.

Presentationally, Amber Rudd was impressive.

But she lacked a command of the detail, which her predecessor had mastered, and it proved to be her undoing."

Before Ms Rudd's resignation, protests in favour of the Windrush immigrants were staged outside the Home Office in London.

Image source, EPA

Image source, EPA

One man was told he would have to pay for prostate cancer treatment as he didn't have the documents to show he was eligible for NHS treatment.

Another, who has been here for five decades - since she was 10 years old - got a letter saying she was in the country illegally and spent a week at Yarl's Wood immigration removal centre.

A third was a baby when he arrived in the UK but was told he did not "exist on any data in this country".

Here are the stories of the people affected by being incorrectly identified as being illegal immigrants.

Rob Watson
BBC political correspondent

"This is a big moment in British politics.

Amber Rudd's resignation is the result not just of the recent row over immigrants from the Caribbean - but allegations over her competence in managing the Home Office.

More important than the complexities of her resignation, however, is the almighty problem it leaves the Prime Minister.

Amber Rudd was one of the most pro-EU voices inside her deeply divided Cabinet, so does Theresa May replace her with another so-called remainer or an enthusiastic brexiteer?

It's a question that comes just as the government faces key and controversial decisions over the UK's future relationship with Brussels." .

• Earlier this year, Labour peer Lord Faulkner raised the case of Paulette Wilson, who had come to Britain from Jamaica in 1968 and had been threatened with deportation
• A number of similar cases were raised and, this month, a petition calling on the Home Office to grant them an amnesty garnered thousands of signatures
• On Wednesday Ms Rudd told MPs investigating Windrush that there were no immigration removals targets
• But an inspection report from December 2015 showed targets for voluntary removals did exist
• Ms Rudd then admitted "local" targets for voluntary removals had been set
• She told the Commons on Thursday she had not been aware of them
• The Guardian then reported a June 2017 memo from an official, copied to Ms Rudd, that refers to targets
• Ms Rudd said she had not seen this memo
• On Sunday evening, the Guardian published a letter from Ms Rudd to Theresa May setting out aims to increase enforced deportations

Amber Rudd's resignation dominates the front pages of Monday's newspapers.

Her "denials are in tatters", the Telegraph writes.

See the front pages here.

More from Amber Rudd's resignation letter.

In her resignation letter, Ms Rudd said she "misled" MPs.

Here's Amber Rudd's resignation letter in full:

The "hostile environment" immigration policy has been blamed for the Windrush scandal.

Earlier this month, the government was forced to apologise after it emerged some children of the so-called Windrush generation had been declared illegal immigrants.

Many were threatened with deportation, denied access to NHS treatment, benefits and pensions and stripped of their jobs.

But what is the "hostile environment" policy?

In the tributes tweeted by Amber Rudd's party colleagues following her resignation, a word that comes up repeatedly is "principled".

Amber Rudd is a former investment banker and financial journalist, who decided to enter politics in her 40s.

She rose rapidly through British politics, becoming home secretary only six years after being elected an MP in 2010.

Ms Rudd - an Edinburgh University history graduate - has two children from the five years she was married to columnist AA Gill.

They separated in 1995. Gill died in 2016.

Former chancellor George Osborne reacts: