For days, they have been denouncing it in Commons debates.
But when it came to a vote on the controversial lockdown measure, 42 Conservative MPs - plus two tellers - voted against it, in a show of strength and bigger-than-expected rebellion.
Boris Johnson comfortably won the vote, by 299 votes to 82, with 23 Labour MPs led by Jeremy Corbyn also defying Sir Keir Starmer and voting with the Conservative rebels against the government.
This was the biggest Tory rebellion Mr Johnson has faced since he became prime minister and, had Labour MPs all voted with the rebels, they could have overturned his 80-seat majority.
And the list of Conservative rebels was not just confined to the usual suspects - the awkward squad who rebel on any subject, given any opportunity - although they joined in, naturally.
The rebels were led by Sir Graham Brady, the chairman of the 1922 Committee, who is Conservative MPs' backbench shop steward and an MP more powerful than most cabinet ministers.
They included grandees like Sir Charles Walker, ex-minister Esther McVey and veterans including David Davis, Sir Christopher Chope, Sir John Redwood and Sir Desmond Swayne from the Tories' libertarian wing.
Then there were serial rebels, hardline Brexiteers and fellow-libertarians like Steve Baker, Peter Bone and Philip Davies and the two "tellers for the Noes", Philip Hollobone and Craig McKinlay.
Worryingly for the prime minister, nine new MPs from the so-called Red Wall seats in northern England rebelled, including Bolton West MP Chris Green, who quit as a junior ministerial aide minutes before the vote.
In a hard-hitting resignation letter to the prime minister, Mr Green said the local lockdown in Bolton had failed and "the attempted cure is worse than the disease".
Others from the 2019 intake who voted against the curfew were Imran Ahmad Khan, James Daly, Tom Hunt, Chris Loder, Antony Mangnall, Gary Sambrook, Matt Vickers and Christian Wakeford.
But these right-wing libertarian Tories had some unlikely left-wing Labour bedfellows in the "No" lobby, led by Mr Corbyn, the former leader, and the former shadow home secretary Diane Abbott.
Other left-wing rebels were Corbyn allies Rebecca Long-Bailey, Dawn Butler, Ian Lavery and Jon Trickett, as the Labour left joined forces with the Tory Right.
From the opposite wing of the Labour Party, Blairite former cabinet minister Ben Bradshaw, along with former defence ministers Kevan Jones and John Spellar and senior MP Chris Bryant, rebelled.
Although the Scottish National Party's MPs did not vote on the curfew in England, 10 Lib Dems, six Democratic Unionist Party MPs and the Green Party's Caroline Lucus opposed it.
The outcome of the vote reveals how brittle support for tougher lockdown measures is on the Tory benches, which is a worrying development for the prime minister as he contemplates further action.
And now that the Labour leader is proposing a "circuit breaker", how do the votes for that in the Commons stack up?
Addressing the 1922 Committee of Tory MPs on a Zoom call, Mr Johnson accused Sir Keir of "playing politics" and "wobbling about like a trolley with a broken wheel".
But after the 44-strong rebellion on the 10pm curfew, it is bound to be suggested that it's the prime minister's own parliamentary colleagues who are veering out of control.
The full list of 42 Conservative MPs who rebelled to oppose the curfew regulations were: Imran Ahmad Khan (Wakefield), Sir David Amess (Southend West), Steve Baker (Wycombe), Harriett Baldwin (West Worcestershire), Bob Blackman (Harrow East), Crispin Blunt (Reigate), Peter Bone (Wellingborough), Sir Graham Brady (Altrincham and Sale West), Sir Christopher Chope (Christchurch), Geoffrey Clifton-Brown (The Cotswolds), James Daly (Bury North), Philip Davies (Shipley), David Davis (Haltemprice and Howden), Dehenna Davison (Bishop Auckland), Jackie Doyle-Price (Thurrock), Richard Drax (South Dorset), Marcus Fysh (Yeovil), Nusrat Ghani (Wealden), Chris Green (Bolton West), Tom Hunt (Ipswich), Pauline Latham (Mid Derbyshire), Chris Loder (West Dorset), Tim Loughton (East Worthing and Shoreham), Anthony Mangnall (Totnes), Karl McCartney (Lincoln), Esther McVey (Tatton), Huw Merriman (Bexhill and Battle), Anne Marie Morris (Newton Abbot), Sir John Redwood (Wokingham), Andrew Rosindell (Romford), Gary Sambrook (Birmingham Northfield), Bob Seely (Isle of Wight), Henry Smith (Crawley), Sir Desmond Swayne (New Forest West), Sir Robert Syms (Poole), Derek Thomas (St Ives), Craig Tracey (North Warwickshire), Matt Vickers (Stockton South), Christian Wakeford (Bury South), Sir Charles Walker (Broxbourne), Giles Watling (Clacton), and William Wragg (Hazel Grove).
The 23 Labour MPs who voted against the regulations, which included the 10pm curfew and other restrictions, were: Diane Abbott (Hackney North and Stoke Newington), Apsana Begum (Poplar and Limehouse), Ben Bradshaw (Exeter), Chris Bryant (Rhondda), Dawn Butler (Brent Central), Jeremy Corbyn (Islington North), Geraint Davies (Swansea West), Andrew Gwynne (Denton and Reddish), Mike Hill (Hartlepool), Rupa Huq (Ealing Central and Acton), Kevan Jones (North Durham), Ian Lavery (Wansbeck), Emma Lewell-Buck (South Shields), Rebecca Long-Bailey (Salford and Eccles), Ian Mearns (Gateshead), Grahame Morris (Easington), Kate Osborne (Jarrow), Bell Ribeiro-Addy (Streatham), Lloyd Russell-Moyle (Brighton Kempton), John Spellar (Warley), Graham Stringer (Blackley and Broughton), Jon Trickett (Hemsworth), and Derek Twigg (Halton).
Ten Liberal Democrats, six DUP MPs and Green Party MP Caroline Lucas also opposed the regulations.