Even in a party with a long history of division, it was still a record-breaker. Last night’s rebellion over Trident was the largest backbench revolt over defence policy since Labour first entered Government in 1924, topping the 79 MPs who defied James Callaghan over defence expenditure in 1977.

Including abstentions Labour’s bachbenchers split down the middle, and the policy only passed thanks to Conservative support.

Thus, three of Tony Blair’s key decisions – foreign policy (Iraq), domestic (education) and defence (Trident) – have all been passed only with the support of the Conservatives.

It did not come out of the blue. For all the talk about sheep and clones after 1997, Mr Blair’s MPs have been a rebellious bunch. They developed a taste for it during Labour’s first two terms when the Government was insulated by its landslide majorities.

Both Government and its MPs found it difficult to adjust when the majority fell in May 2005. Since then the Government have been defeated on four occasions, a postwar record for an administration with a majority of over 60, and survived other revolts only by a series of retreats and deals.

The MPs that the Government should be most worried about are those who rebelled for the first time last night and may now develop a taste for doing so again. The majority of MPs who in 2003 defied the whip for the first time over Iraq, later went on to rebel a second time.

The majority of yesterday’s virgins will do the same, storing up trouble for Labour’s next Prime Minister.

Both John Major and Mr Callaghan enjoyed short term honeymoons with their backbench-ers after taking office – only for all hell to break loose once the honeymoon ended.

Gordon Brown should fear the same.

The Labour rebels

Diane Abbott (Hackney North & Stoke Newington), John Austin (Erith & Thamesmead), Anne Begg (Aberdeen South), Joe Benton (Bootle), Roger Berry (Kingswood), Karen Buck (Regent’s Park & Kensington North), Richard Burden (Birmingham Northfield), Colin Burgon (Elmet), Ronnie Campbell (Blyth Valley), Martin Caton (Gower), David Chaytor (Bury North), Katy Clark (Ayrshire North & Arran), Charles Clarke (Norwich South), Harry Cohen (Leyton & Wanstead), Michael Connarty (Linlithgow & Falkirk East), Frank Cook (Stockton North), Jeremy Corbyn (Islington North), Jim Cousins (Newcastle upon Tyne Central), Jonathan Cruddas (Dagenham), Ann Cryer (Keighley), John Cummings (Easington). Ian Davidson (Glasgow South West), Janet Dean (Burton), Jim Devine (Livingston), Jim Dobbin (Heywood & Middleton), Frank Dobson (Holborn & St Pancras), Frank Doran (Aberdeen North), David Drew (Stroud), Clive Efford (Eltham), Jeff Ennis (Barnsley East & Mexborough), Bill Etherington (Sunderland North), Mark Fisher (Stoke-on-Trent Central), Paul Flynn (Newport West), Michael Jabez Foster (Hastings & Rye), Neil Gerrard (Walthamstow), Dr Ian Gibson (Norwich North), Roger Godsiff (Birmingham Sparkbrook & Small Heath), Nia Griffith (Llanelli), John Grogan (Selby). David Hamilton (Midlothian), Fabian Hamilton (Leeds North East), Dai Havard (Merthyr Tydfil & Rhymney), David Heyes (Ashton under Lyne), Kate Hoey (Vauxhall), Kelvin Hopkins (Luton North), Eric Illsley (Barnsley Central), Glenda Jackson (Hampstead & Highgate), Sian James (Swansea East), Dr Lynne Jones (Birmingham Selly Oak), Peter Kilfoyle (Liverpool Walton), Mark Lazarowicz (Edinburgh North & Leith), David Lepper (Brighton Pavilion), Tony Lloyd (Manchester Central). Christine McCafferty (Calder Valley), John McDonnell (Hayes & Harlington), Ann McKechin (Glasgow North), Andrew Mackinlay (Thurrock), David Marshall (Glasgow East), Bob Marshall-Andrews (Medway), Michael Meacher (Oldham West & Royton), Alan Meale (Mansfield), Austin Mitchell (Great Grimsby), Julie Morgan (Cardiff North), George Mudie (Leeds East), Chris Mullin (Sunderland South), Denis Murphy (Wansbeck), Dr Doug Naysmith (Bristol North West), Sandra Osborne (Ayr, Carrick & Cumnock). Stephen Pound (Ealing North), Gordon Prentice (Pendle), Ken Purchase (Wolverhampton North East), Linda Riordan (Halifax), Chris Ruane (Vale of Clwyd), Joan Ruddock (Lewisham Deptford), Mohammad Sarwar (Glasgow Central), Alan Simpson (Nottingham South), Marsha Singh (Bradford West), Dennis Skinner (Bolsover), Andrew Smith (Oxford East), Sir Peter Soulsby (Leicester South), Ian Stewart (Eccles), Dr Howard Stoate (Dartford), Gavin Strang (Edinburgh East), Graham Stringer (Manchester Blackley), Jon Trickett (Hemsworth), Paul Truswell (Pudsey), Dr Desmond Turner (Brighton Kemptown), Rudi Vis (Finchley & Golders Green), Joan Walley (Stoke-on-Trent North), Robert Wareing (Liverpool West Derby), Betty Williams (Conwy), David Winnick (Walsall North), Mike Wood (Batley & Spen), Anthony Wright (Great Yarmouth). Labour's David Taylor (Leicestershire North West) was the teller for the Ayes

Philip Cowley is professor of parliamentary government at the University of Nottingham and author of The Rebels (Politico’s 2005)

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