By Guy Faulconbridge and Michael Holden
LONDON (Reuters) - When Gina Miller took the British government to court over triggering Brexit, she didn't expect death threats or the need to bring in security so that her children could get to school safely.
A successful London investment manager, Miller was assigned by a judge to be the lead claimant in a court case brought by members of the public, which challenged Prime Minister Theresa May's authority to start talks to pull Britain out of the European Union without first asking parliament.
Since a panel of three High Court judges ruled in her favor last month, she has received relentless racist and sexist intimidation, including e-mails warning she would be gang raped and calling for her to be run down on the street.
The government has appealed the case, which goes before Britain's Supreme Court next week.
Miller, 51, has reported the threats to the police who she said were likely to speak to or arrest five people any day. She has spent 60,000 pounds for her own protection including dealing with attacks on the website of her business.
The experience of what she describes as a "poisoned chalice" legal challenge has revealed how divided Britain has become since the EU referendum campaign in which one lawmaker, Jo Cox, was killed on the street by a Nazi-obsessed loner.
"This division was always there but Brexit perhaps has been irresponsible: Those who were talking about leaving in particular have emboldened people to think such behavior is acceptable," Miller told Reuters at a temporary office which she has leased for security reasons. "It's revealed a side to society which is extremely worrying."
She was born in what was then Britain's South American colony British Guiana, now the independent state Guyana, and sent to school in Britain by her parents. A selection of the threatening emails she has received, which she showed to Reuters, was littered with racist slurs as well as sexist obscenities.
"The levels of sexual and racial violence have been quite extraordinary, to the level that because I'm a 'colored woman' I don't have any place outside of a kitchen."
Some of the hatred, she says, arises from right wing media focusing on her biography to discredit her.
Britain's most widely-read newspaper, The Sun, called her a "foreign-born millionaire", an epithet that, she notes, the paper doesn't use to describe its own Australian owner Rupert Murdoch, or Britain's New York-born foreign secretary.
"You don't see Boris Johnson described as 'foreign-born'," she said. "I am British. I went to a British school, I pay British taxes and my children are British."
The Brexit campaign is not her first foray into public policy. Previously, Miller, who founded investment manager SCM Private with her hedge fund manger husband Alan, advocated for more transparency around fund management fees and financial product charges. That galled some asset managers in London, but produced nothing like the anger of Brexit.
While supporters feted Miller for her legal action against the government, opponents have cast her as a wealthy pawn of an establishment which wants to soften or slow Brexit in defiance of the wishes of the people.
In the June 23 referendum, 51.9 percent, or 17.4 million people, voted to leave the EU while 48.1 percent, or 16.1 million people, voted to stay.
If Miller's victory is upheld in the Supreme Court, the government would be forced to accept a vote in parliament over starting the formal EU divorce talks which are triggered by invoking Article 50 of the Lisbon Treaty. That could delay Brexit and increase scrutiny of May's negotiation.
Miller, who describes herself as a "born fighter" and "a failed lawyer", felt physically sick when she heard the referendum result, but says her goal is not to block Britain's exit from the European Union.
She says prime ministers should not be allowed to undermine 400 years of parliamentary sovereignty. She also dismisses the idea that she is a representative of an out of touch elite.
"My principles have been exactly the same from when I slept three weeks in a car because I had no money, to being a single parent doing four jobs to pay for myself through university, having no food, I have had both extremes," she said.
"What is wrong with me now using my money that I have worked very, very hard for to do what I think is right?" said Miller. She is being represented by London law firm Mishcon de Reya, which agreed not to charge legal fees.
The case was brought on behalf of a group of campaigners but Miller became its face when she was assigned the role of lead claimant by one of Britain's top judges. The second named claimant is Deir Tozetti Dos Santos, a Brazil-born hairdresser. Both are British citizens.
Before the High Court hearing, May suggested that people bringing such cases were attempting to subvert democracy. After three of England's top judges ruled against the government at the High Court, the Daily Mail newspaper cast the bewigged justices as out of touch "enemies of the people".
Since the High Court ruling, May has said she values the independence of the judiciary and the freedom of the press. But critics have faulted the government for failing to defend the judges more vociferously.
Miller said Britain's political leaders, including in the opposition Labour Party, were too afraid to confront the emotion unleashed by the referendum.
"They're being silent because everything to do with Brexit is so emotionally charged that they're hiding and they're quite happy for me to take the blame and be in the headlines and take the threats while they sit around and figure out what they do."
Even more anger will be unleashed if Brexit turns out not to improve the lives of those who supported it, she added.
"You've woken up an element in society and promised them their lives are going to get better. And when their lives don't get better they are going to be even more angry than they are now," she said. "The politicians are setting themselves up for a really, really dangerous future."
The Brexit case is based on legal arguments about Britain's constitution that go back centuries. The government argued that it could invoke Article 50 without lawmakers' approval using "royal prerogative", the power of ministers to act on behalf of the monarch, especially when making or withdrawing from foreign treaties.
Miller's lawyers argued that quitting the EU would deprive people of rights, which is prohibited without parliament's approval under 17th century court rulings and the 1688 Bill of Rights. The High Court agreed.
The BBC has reported that the government has prepared a brief bill of just three lines to send to parliament, in case the Supreme Court upholds the ruling. Miller said that she would want to see a full and properly drafted act.
"There needs to be more than two paragraphs, it needs to be a properly drafted act," Miller said. "If you are going to take away people's rights, inevitably by triggering Article 50, there has to be a discussion about the direction of travel."
The Supreme Court, which agreed to hear the appeal, has added another constitutional wrinkle to the case: it will allow lawyers for Scotland to argue that the Scottish legislature should also have a say before Brexit.
"They're allowing quite a number of cans of worms to be opened by doing this appeal," said Miller. "Here we are with Brexit -- leaving -- and we have not answered the fundamental questions."
(Editing by Peter Graff)