Rebel Labour and Tory MPs defied their party leaders and joined an SNP-led attempt to delay Brexit.
Jeremy Corbyn had whipped his MPs to abstain on an amendment to Theresa May’s plan B Brexit deal, tabled by their Scottish rivals, to extend the Article 50 deadline by a maximum of three months.
MPs rejected the amendment by 93 to 315 but the news is further proof of deep party splits over Brexit.
A total of 41 Labour MPs, including well-known ‘Remainers’ Chuka Umunna, Luciana Berger and Stella Creasy, ignored party chiefs to join the SNP and the Lib Dems in the voting lobbies.
It comes amid fresh speculation that Labour MPs are preparing to form a breakaway party, with “six to ten” reported to be ready to resign.
The Labour rebels
Debbie Abrahams (Oldham East and Saddleworth)
Tonia Antoniazzi (Gower)
Luciana Berger (Liverpool, Wavertree)
Ben Bradshaw (Exeter)
Karen Buck (Westminster North)
Ruth Cadbury (Brentford and Isleworth)
Ann Clwyd (Cynon Valley)
Ann Coffey (Stockport)
Neil Coyle (Bermondsey and Old Southwark)
Mary Creagh (Wakefield),
Stella Creasy (Walthamstow)
Janet Daby (Lewisham East)
Geraint Davies (Sansea West)
Rosie Duffield (Canterbury)
Paul Farrelly (Newcastle-under-Lyme)
Mike Gapes (Ilford South)
Kate Green (Stretford and Urmston)
Helen Hayes (Dulwich and West Norwood)
Meg Hillier (Hackney South and Shoreditch)
Margaret Hodge (Barking)
Susan Elan Jones (Clwyd South)
Ged Killen (Rutherglen and Hamilton West)
David Lammy (Tottenham)
Chris Leslie (Nottingham East)
Anna McMorrin (Cardiff North)
Madeleine Moon (Bridgend)
Ian Murray (Edinburgh South)
Albert Owen (Ynys Mon)
Barry Sheerman (Huddersfield)
Gavin Shuker (Luton South)
Andy Slaughter (Hammersmith)
Angela Smith (Penistone and Stocksbridge)
Owen Smith (Pontypridd)
Jo Stevens (Cardiff Central)
Gareth Thomas (Harrow West)
Chuka Umunna (Streatham)
Keith Vaz (Leicester East)
Catherine West (Hornsey and Wood Green)
Martin Whitfield (East Lothian)
Paul Williams (Stockton South)
Daniel Zeichner (Cambridge)
Tory MPs Ken Clarke and Sarah Wollaston, both veteran europhiles, also rebelled against government whips, while ardent Labour Brexiteer joined with the Tories to vote against it.
Corbyn’s official position is to back an extension to Article 50 with many of his frontbenchers slating government “chaos” and the threat of no-deal.
But whips told Labour MPs to refrain from backing the three-month delay put forward by Nicola Sturgeon’s party.
Shadow Brexit Secretary Keir Starmer has said he favours a separate plan by party backbencher Yvette Cooper to avoid no-deal by writing a Brexit delay into new legislation.
The backbencher is not likely to launch her amendment to the PM’s Brexit plan - which will see parliament seize control of Brexit if May has no viable deal by mid-March - until February 27.
The vote came as May faced a fresh Commons defeat her eurosceptic MPs helped Labour to inflict.
May had hoped to show Brussels she had a “stable” majority for her recent diplomatic push to revise her plans, but Conservative backbenchers instead defied her.
The PM saw her authority yet again undermined by her own party as the Commons voted by 303 to 258 against her deal.
Just 243 Tories backed May, with nearly a quarter of her MPs deciding to pull their support. Five Tories voted against and 67 abstained.