The Tory peer had backed demands for a “meaningful vote” on the final Brexit deal and led the fight for the amendment.

On Tuesday evening, Lord Heseltine was eating dinner with his wife when he was informed that the Prime Minister was firing him from his roles advising the Government on a number of areas, including its industrial strategy.

Speaking on BBC Radio 4’s Today, he said: “I have never met Theresa May so I can’t make a judgement. She’s doing very well in the polls… the public approve of what she’s doing.”

The peer said had been working for the Government three to four days a week for the last six years, but that he had “no relationship” with Mrs May, was sacked by the chief whip in the Lords, and has still not heard from Number 10

Speaking in the Lords last night he stated that quitting the European Union was the “most momentous peacetime decision of our time”.

He told the Lords that he “deeply” regretted the outcome of last year’s EU referendum and that “the fightback starts here”.

He told the BBC that he believed Mrs May was “exercising her perfectly legitimate right to get rid of opposition in any way she finds appropriate”.

“Whether it’s a wise thing to do is a matter for her not for me,” he said.

“I have been hugely proud of the work I have done for David Cameron and now for this prime minister, and if they don’t want me to go on they must sack me.

“I did write a newspaper article the other day setting out exactly what I intended to do so I think they could have told me this would be the price, but let me make it quite clear; I would still have voted as I did tonight.

“Sometimes in politics there are issues which transcend party politics; in the end you have to be your own person. I believe our interests are intertwined with Europe. I am not prepared to change.

“Every Conservative prime minister I worked for has told me, including this prime minister before the referendum, that we were essentially seeking British self-interest in Europe.

“It’s not perfect but it’s much better than anything that happened before the Second World War.”

He explained in an interview on Sky News that he had decided to deliver such a strong anti-Brexit speech because he “had to be true” to himself.

“I have been working for the Government now for six years. It has been a privilege,” he said.

“Of course I’m very sad and sorry to see it go – but in the end you have to be true to yourself and I knew I had to make that speech today in the House of Lords.

“None of us can see what governments we’re going to be dealing with in Europe. We can’t see what the circumstances are going to be, we can’t see what the deal is going to be.

“All people like me in the House of Lords are saying is that the ultimate sovereignty of this country lies in Parliament. That’s what the Brexit people have been saying along: ‘We’ve got to have sovereignty back.'”

In Lord Heseltine’s six years as a Government adviser, he was asked to help the Government with plans to restore deprived estates under David Cameron and he also worked with George Osborne on plans for east London.

He advised on plans for a Swansea city deal and has been working with the Department for Business, Energy and Industrial Strategy.

Lord Heseltine was also a national infrastructure commissioner.

The amendment was passed by 366 votes to 268 in the Lords and the Article 50 bill will now return to the Commons for its final reading next week.

Up to 20 Conservative MPs could vote in favour of the amendment, with rebels encouraging others to abstain.

The Government has a “Brexit majority” of around 30 MPs – double its normal working majority – because it can count on the support of a number of MPs from other parties.

The danger for Mrs May is that the Lords vote on the amendment could encourage Conservative MPs representing pro-Remain constituencies to abstain.

David Davis, the Brexit Minister, said in a statement that the Government would seek to overturn the changes.

“It is clear that some in the Lords would seek to frustrate that process, and it is the Government’s intention to ensure that does not happen. We will now aim to overturn these amendments in the House of Commons,” Mr Davis said.

The Government has already promised Parliament a vote on the final deal, but believes restricting Mrs May’s ability to leave the negotiating table could encourage the EU to offer a bad deal in the hope that MPs would then reject it and potentially halt Brexit.

“This amendment simply makes the negotiations much harder from day one for the Prime Minister as it increases the incentive for the European Union to offer nothing but a bad deal,” said George Bridges, the government’s Brexit minister for the Lords, in his final plea before the vote.