Today is traditionally the day when the Opposition digs out the gremlins hiding in the detail of the Budget – terms like “Granny Tax” and “Pasty Tax” have been coined on post-Budget Thursdays.

It’s a sign of the weakness of Corbyn and McDonnell that they haven’t thus far posed a serious threat to the Chancellor’s proposals. Instead, the first real trouble seems to be coming from the Conservative backbenches, specifically over the question of cuts to the Personal Independence Payment (PIP) which support disabled people of working age.

The cut in question aims to save £1.3 billion a year by 2020, and the IFS says it will affect 370,000 of the 2.4 million PIP claimants by that date – meaning they would lose £3,500 a year on average.

That has seriously worried some Tory MPs. A letter expressing concern has been circulating, others have expressed outright opposition and Andrew Percy sounded confident on the World at One this afternoon that there would be sufficient Tory rebels to defeat the Government on the issue:

Percy has tweeted that he would prefer to see “a penny or two on fuel” duty to avoid this cut – a bold statement but also a responsible one, showing he is willing to recognise that cancelling one saving must mean finding the money from elsewhere.

Another possible rebel is Johnny Mercer:

As Paul Waugh spotted this morning, Osborne has left the door open for a possible retreat on the policy. If he does change tack, where will he find the extra money?