11:52

Labour anticipates that the principal vote on the budget - at which the DUP and any Tory rebels would have to stand up and be counted - will take place around 5pm on Thursday 1 November, three days after Philip Hammond’s speech.

Losing a vote on a budget would normally be expected to lead to a vote of confidence given that the government’s authority rests on its ability to get finance bills through the Commons.

But some Labour insiders wonder if the budget could be carefully constructed so that it had no substantive measures that required MPs’ authorisation, making it more in line with now abolished autumn statements. But that would leave Hammond with little to announce, and the technicality may be lost on the public.

Another theoretical possibility is that rebels try to force a vote on budget day itself - by opposing the ways and means resolutions that authorise changes to excise on wines and beers and other similar duties that typically come into force on midnight of budget day itself. That, however, would require some quick decision making, because these resolutions are put to MPs shortly after Hammond sits down and rebels would not know what the changes in duties were until Hammond had told the house in the budget speech.