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Gina Miller, the businesswoman who has now won two Supreme Court victories over the government, tells the BBC that the verdict should be celebrated by everyone, regardless of their views on Brexit.

"It is an extraordinary judgement because of the landmark nature of the case and the ruling," she says.

She says there is now a constitutional precedent that a prime minister cannot "overstep the mark" in shutting down Parliament for this length of time.

Mrs Miller previously won a case which gave MPs the right to vote on invoking Article 50, which began the Brexit process.

"Twice in three years I’ve had to bring a case all the way to the Supreme Court to defend parliamentary sovereignty, which is the absolute pillar of our democracy," she says.

"That is something anybody, irrespective of how you voted, irrespective of your cause, should be celebrating."

She says MPs should return to work as soon as possible and Mr Johnson "should be considering his position", but added that is a matter for politicians.

Mrs Miller was "nervous" right up until the verdict was given. "I was told there was no way it would ever be heard, much less win," she says.

"I had to press forward with what I believed was right, which was holding the prime minster to account."

Having previously spoken about the personal cost to her of these legal challenges, which have brought her personal threats, Mrs Miller says: "The right thing to do tends to come at a cost. It is a cost worth paying from my point of view."

Speaker of the House of Commons John Bercow says that Parliament will resume tomorrow at 11:30 BST.

He says there will be no Prime Minister's Questions, which are usually scheduled on a Wednesday, because of "notification requirements".

But he adds that there will be opportunities for MPs to hold the government to account over the Supreme Court case.

"For the avoidance of doubt there will be full scope for urgent questions, for ministerial statements and applications for emergency debates under standing order 24," he says.

He says the court's unanimous, unambiguous and unqualified verdict is "the prorogation of Parliament is unlawful, unlawful because it frustrated or prevented Parliament from the discharge of its core duties and it did so at a crucial time for our country".

Mr Bercow says "the citizens of the UK are entitled to expect" that Parliament will be able to carry out its core functions of scrutiny, holding the government to account and legislating, if it chooses.

Supreme Court President Lady Hale's delivery of today's ruling put PM Boris Johnson front and centre of the UK's news... but on social media she was herself becoming something of a talking point, even trending second on Twitter.

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Liberal Democract MP Chuka Umunna tells the BBC the prime minister should resign and MPs need to form an emergency government to replace this "dysfunctional" one.

He says it is "a good day for democracy" and "a damning indictment of the prime minister and the government"

"It is quite unprecedented. This is not normal for a prime minister to be declared to having acted in an unlawful fashion. In those circumstances you would expect the prime minister to resign, that is what should happen now," he said.

He said the Commons should resume sitting tomorrow.

"It should be Prime Minister's Questions if the prime minister hasn't resigned by that point, and then I think we need to form some sort of emergency government because the government we've got now is dysfunctional, it's not sustainable," he says.

"The leader of the Liberal Democrats Jo Swinson has put forward the Mother and the Father of the House Harriet Harman and Ken Clarke as people who could potentially lead that emergency government, but we can't carry on like this."

The latest episodes of Brexitcast can be found on the BBC Radio 5 Live website.

Image source, EPA

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Buckingham Palace has not yet commented on the ruling.

The Queen is still at Balmoral in the Scottish Highlands, where she is spending her annual summer break.

Twitter

As of midday in the UK, all of the top five Twitter trends relate to to the fall-out from today's Supreme Court ruling.

The trends are:

1. #SupremeCourt
2. #LadyHale
3. #Prorogation
4. #ByeByeBoris
5. #ResignBoris

Peter Barnes
BBC political analyst

The Supreme Court has ruled the suspension of Parliament on 9 September was unlawful and void. MPs may now return to Westminster in the coming days.

A law designed to stop a no-deal Brexit on 31 October has been passed. If a deal is not agreed between the UK and EU by 19 October, and MPs don't vote in favour of leaving without a deal, then the prime minister will be legally obliged to ask the EU for a Brexit delay.

There are a number of scenarios that could now happen.

Continuing reading here.

Shadow Attorney General Shami Chakrabarti says Boris Johnson has behaved like a "tin-pot dictator" and praises the court for demonstrating no one is above the law.

"Lady Hale, the president of the Supreme Court, has given an amazing judgement that will be read and remembered up and down these islands, across the world, for many years to come," she tells the BBC.

"No one is above the law, not even Boris Johnson and his arrogant entitled chums.

"He has behaved like a tin-pot dictator and he has been called out by the highest court in the land."

She says Mr Johnson should be "thoroughly ashamed".

"He’s had an elite education, has had every opportunity in life and he’s behaved appallingly," she says.

"We teach our kids to obey the police and respect the local magistrate, how will we be able to set an example if the prime minister does not now reflect on being called out by the highest court in the land?"

BBC News Channel

Richard Tice, chairman of the Brexit Party, tells the BBC that today's decision is "seismic, historic" but MPs must think about what happens next.

"As soon as Parliament is recalled tomorrow, Boris Johnson is probably going to have to offer his resignation," he says.

"There may well be a vote of no confidence."

He says the public must now realise that "we're not leaving the EU on 31 October".

"There will have to be an extension. When that penny drops, people are going to be increasingly angry across the country," he says.

Mr Tice says there will probably have to be an election in the first half of November.

"What does it say about the so-called master strategist Dominic Cummings? I trust he will be offering his resignation today."

Image source, Getty Images

Labour MP Hilary Benn says Boris Johnson "owes Parliament a very, very big apology" and should "consider his position".

"The court has ruled that the prorogation never happened, it was null and void, we won’t be going back to a Queen’s speech, we’ll be going back to work," he says.

"I hope it will be as soon as possible. I trust the Speaker will make clear how quickly Parliament will return."

BBC Radio 5 Live

Jonny Dymond
BBC royal correspondent

The palace is unsurprisingly being very tight lipped on this. When the ruling came down from the Scottish Court of Session, the only word from a palace source was, “the Queen acts, and has acted, on the advice of her prime minister”.

It has to be said there is very, very little discretion for the Queen when it comes to prorogation. The advice is with a capital A. She is effectively being told to prorogue.

There is one tiny, tiny sliver of good news for Boris Johnson, which is that the court did not say he misled the Queen, which would have been even more embarrassing situation.

But talk of embarrassment, having an Order in Council, an act by the Sovereign, declared unlawful by the court, null and void and having no effect – I’ve been looking through the precedents and I can’t find a precedent.