Ken Clarke has said he will vote against Brexit, during a speech in which the veteran Conservative MP accused his own party of being “anti-immigrant” and claimed even Enoch Powell would be surprised at how Eurosceptic the Tories had become.

In a impassioned address that made a powerful argument for MPs voting with their conscience rather than following their constituents, the former Chancellor said Brexit was “baffling” to the UK’s allies abroad and claimed leaving the EU was “a very, very bad move, particularly for our children and grandchildren”.

Mr Clarke announced he would be voting against the Government’s position and instead backing an amendment tabled by the Scottish National Party to prevent Article 50 being triggered.

Referencing the anti-immigrant former Tory MP Enoch Powell, whom he called “the best speaker of the Eurosceptic cause”, Mr Clarke said: “If he was here he would probably find it amazing to believe that his party had become Eurosceptic and rather mildly anti-immigrant in a very strange way in 2016. I’m afraid on that I haven’t followed them – and I don’t intend to do so.”

His claims were greeted with heckling, tutting and head-shaking from his Conservative colleagues, but Mr Clarke returned fire.

In a barely coded attack on fellow Tory MPs who advocated a Remain vote but are now voting to for Brexit, he said: “I admire my colleagues who can suddenly become enthusiastic Brexiteers having seen a light on the road to Damascus on the day the votes were cost on 23 June. I’m afraid that light has been denied me.”

Mr Clarke is the first Conservative MP to announce he will vote against the party whip and oppose the Prime Minister’s efforts to begin the process of withdrawing Britain from the EU.

Defending the decision, he said: “I would point out to those who say that somehow I am being disloyal to my party by not voting in favour of this Bill: I am merely propounding the official policy of the Conservative Party for 50 years until 23 June 2016.

Supreme Court Brexit Challenge Show all 13 1 /13 Supreme Court Brexit Challenge Supreme Court Brexit Challenge People wait to enter the public gallery outside the Supreme Court ahead of the challenge against a court ruling that Theresa May's government requires parliamentary approval to start the process of leaving the European Union, in Parliament Square, central London Reuters Supreme Court Brexit Challenge Gina Miller, co-founder of investment fund SCM Private arrives at the Supreme court in London on the first day of a four-day hearing Getty Supreme Court Brexit Challenge A man waves the EU flag in front of the Supreme Court Getty Supreme Court Brexit Challenge Satirical artist Kaya Mar poses with two of his paintings in front of the Supreme Court Getty Supreme Court Brexit Challenge Pro-Europe protestors dressed as Supreme Court Justices stand outside the Supreme Court ahead of the first day of a hearing into whether Parliament's consent is required before the Brexit process can begin. The eleven Supreme Court Justices will hear the government's appeal, following the High Court's recent decision that only Parliament can trigger Article 50 Getty Supreme Court Brexit Challenge The eleven Supreme Court Justices will hear the government's appeal, following the High Court's recent decision that only Parliament can trigger Article 50 Getty Supreme Court Brexit Challenge Businesswoman Gina Miller arrives at the Supreme Court ahead of the first day of a hearing into whether Parliament's consent is required before the Brexit process can begin Getty Supreme Court Brexit Challenge Attorney General Jeremy Wright arrives at the Supreme Court in London EPA Supreme Court Brexit Challenge Protesters outside the Supreme Court in London, where the Government is appealing against a ruling that the Prime Minister must seek MPs' approval to trigger the process of taking Britain out of the European Union PA wire Supreme Court Brexit Challenge A protesters wearing a judge's wigs and robes stands outside the Supreme Court ahead of the challenge against a court ruling that Theresa May's government requires parliamentary approval to start the process of leaving the European Union, in Parliament Square, central London Reuters Supreme Court Brexit Challenge A protester holds up a placard outside the Supreme Court ahead of the challenge against a court ruling that Theresa May's government requires parliamentary approval to start the process of leaving the European Union, in Parliament Square, central London Reuters Supreme Court Brexit Challenge Pro-Europe protestors dressed as Supreme Court Justices stand outside the Supreme Court Getty Supreme Court Brexit Challenge A man waiting to enter the public gallery waves a European Union flag outside the Supreme Court ahead of the challenge against a court ruling that Theresa May's government requires parliamentary approval to start the process of leaving the European Union, in Parliament Square, central London Reuters

He also criticised those suggesting MPs should follow the vote of their constituents, saying: “I have fought Lord knows how many elections and I have always advocated voting Conservative.

“But the British public, in their wisdom, have occasionally failed to take my advice and they have actually by a majority voted Labour and I have found myself here facing a Labour government.

“I do not recall an occasion where I have been told it was now my democratic duty to support Labour policies and the Labour government”.

Mr Clarke also mocked Brexit supporters claiming the EU had a bright future as a “trading nation”.

He said: “Apparently you follow the rabbit down the hole and you emerge in a wonderland where suddenly countries throughout the world are queuing up to give us trading advantages and access to their markets that previously we’ve never been able to achieve as part of the European Union.

Labour MPs lavished praise on Mr Clarke’s speech, with some taking the unusual step of applauding in the House of Commons chamber.

Angela Eagle, a former Treasury Secretary, said Mr Clarke was “making total mincemeat” of the Government’s Brexit position, while former minister David Lammy called it a “truly great speech”.