The government has been dealt a huge blow after a High Court ruled that MPs must be able to vote before Theresa May triggers Article 50.
The ruling means the prime minister must consult with parliament before beginning the process of UK leaving the EU.
A Government spokesperson said they are “disappointed” by the ruling from Lord Chief Justice Lord Thomas and two other senior judges and will be appealing the decision.
The announcement arrived following a so-called “People’s Challenge” against Brexit, spearheaded by campaigner .
Following the ruling, Miller said outside the court the claim was “about process not politics.” She added: “It’s about our United Kingdom and all our futures. It’s not about how anyone voted.
“Every one of us voted for the best country and the best future.”
“The judgment, I hope – when it’s read by the Government and they contemplate the full judgment – that they will make the wise decision of not appealing but pressing forward and having a proper debate in our sovereign parliament, our mother of parliaments that we are so admired for all over the world.”
Miller, 51, was born in Guyana but grew up in Britain and currently works as an investment manager at London-based firm SCM Private – a company she founded with her husband in 2014.
The entrepreneur launched two marketing businesses in the 90s – Sway Marketing and Senate Programme – before later starting Wilde marketing Consultancy in 2006.
Miller is also known as a keen philanthropist, launching the Miller Philanthropy in October 2009 – which later became the True and Fair foundation – as well as contributing huge amounts to the Margaret Thatcher infirmary at the Royal Hospital Chelsea.
She also has a history of taking on major establishments, with the True and Fair Foundation main objective described as “small charities by providing funding and practical support to enable them to meet their own objectives.”
The foundation also called for an end to hidden fund charges dealings in and less “smoke and mirrors” in the City of London’s fund management dealings.
She met her husband, Andy, following the breakdown of his second marriage. He is described as the original “Mr Hedge Fund” after amassing a fortune of more than £30m ($37m) working in the City.
Speaking in August about her decision to launch the appeal, Miller told Business Insider: “I believe these things should be debated and looked at in parliament. It would be the first time that we would have a proper, serious, grown-up debate about all the factors that will influence us leaving the EU.
“There should be a debate about the consequences for different sectors. MPs should listen to their constituents. Then, if MPs vote in favour of invoking Article 50, primary legislation.”