Having voted against the Labour amendment on Syria at 10pm on Thursday, Justine Greening, the International Development Secretary, and Mark Simmonds, the Foreign Office Minister, went off to a small meeting room near the Commons chamber, which ministers often use between votes. They were, it is understood, discussing the situation in Rwanda.
The key vote on the Coalition motion was expected to begin at 10.15pm. The division bells duly rang out to alert MPs but Ms Greening and Mr Simmonds apparently did not hear them.
A Commons spokesman said: "Both divisions proceeded as normal last night with division bells and the usual audio/visual indications on the hundreds of monitors around the estate."
The division bells, which normally ring out loudly, were tested yesterday morning and were working correctly, he said.
"There would have been a lot of activity there around those (meeting) rooms. It would have been clear that there had been a division on," he added.
David Cameron said his missing colleagues had apologised for their non-appearance. "I have accepted that apology. It wouldn't have changed the result," he said.
But it emerged that, in total, some 10 ministers and government aides were not present for the all-important vote, which the UK Government lost by 13 votes. Some, who were on family holidays, had permission to be absent.
The only Scottish rebel was Michael Crockart, the LibDem MP for Edinburgh West, who voted for neither the Government motion nor the Labour amendment, saying: "The risks of hasty military intervention are greater than those of stepping back from an attack."
If all the missing ministers had all turned up, Mr Cameron would only have had to persuade four more absent MPs, who included Tim Farron, the Liberal Democrat President, to win the vote
Some 39 Coalition MPs, 30 Tories and nine LibDems, voted against the motion supporting the principle of military action.