Shadow Business Secretary Clive Lewis has resigned amid the vote on Brexit
The shock resignation came as MPs voted on whether Prime Minister Theresa May should be allowed to trigger Article 50 and start the formal process for the UK to leave the EU.
Mr Lewis is the fourth shadow cabinet MP to leave as the UK negotiates its future.
His resignation came as the third reading of the EU notification bill took place late on Wednesday night. It signified the final vote at the House of Commons before it goes to the House of Lords.
And it was this vote that Mr Lewis felt that he could not support.
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Labour leader Jeremy Corbyn said that he understood the difficulty that Mr Lewis had faced
He said in a statement: "When I became the MP for Norwich South, I promised my constituents I would be 'Norwich's voice in Westminster, not Westminster's voice in Norwich'.
"I therefore cannot, in all good conscience, vote for something I believe will ultimately harm the city I have the honour to represent, love and call home.
"It is therefore with a heavy heart that I have decided to resign from the shadow cabinet."
Mr Lewis added that working with the shadow cabinet and Labour Party leader My Corbyn had "been a privilege."
He added that he would "continue to support our party and our leader from the back benches to the very best of my ability."
Liberal Democrat leader Tim Farron described Mr Lewis' move as"noble"
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Labour leader Jeremy Corbyn called Mr Lewis an "asset to the party" and said he "understands the difficulties for MPs representing constituencies that voted remain."
Mr Corbyn said: “I would like to thank Clive for his work in the shadow cabinet, which has underlined what an asset he is to the Labour party and our movement."
“I understand the difficulties MPs representing constituencies which voted remain have in relation to the European Union withdrawal bill. MPs have a duty to represent their constituents as well as their party. However, the Labour party respects the outcome of the EU referendum, so we have asked all Labour MPs to vote for the bill at its third reading tonight.”
Meanwhile, Liberal Democrat leader Tim Farron described his actions as a "noble thing to do."
Mr Lewis was just the latest casualty from the labour front benches to quit after Mr Corbyn’s decision to whip his MPs to back Brexit.
MPs votes were announced tonight on triggering Article 50
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Britain's most senior judges ruled that Prime Minister Theresa May does not have the power to trigger the formal process Article 50 for the UK's exit from the European Union without Parliament having a say.
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Issued by the Supreme Court of (top row, from the left) Lord Neuberger, Lord Mance, Lord Kerr, Lord Sumption, (bottom row, from the left) Lady Hale, Lord Clarke, Lord Wilson and Lord Hodge, who agreed with the majority decision that the Government could not trigger Article 50 without Parliamentary approval.
The prime minister got the nod of approval from MPs to push ahead with triggering Article 50 during a decisive House of Commons vote this evening.
MPs tonight voted 494 to 122 in favour of approving the European Union (Notification of Withdrawal) Bill, which will now proceed to the House of Lords.
Despite a Labour rebellion, which saw a number of MPs ignore Jeremy Corbyn’s three-line whip, the bill passed by a clear 372 majority at 8.15pm this evening.
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