It had previously been suggested that the defence budget may increase amid concerns about the UK’s readiness for war if the conflict in Ukraine draws in Nato countries.

Privately, the prospect of Vladimir Putin pushing into other European states has been described as an “elephant in the room” that Downing Street would prefer to ignore.

Ministers are already planning to reduce troop numbers from 82,000 73,000 by 2025, while the high rate of inflation means the defence budget is shrinking in real terms, despite the planned top-up from the Integrated Review.

All department bids ‘harshly rebuffed’

Analysis by the Royal United Services Institute (RUSI), a leading defence think tank, found that when inflation was taken into account, defence spending would actually fall in real terms in 2023 and 2024.

It has been suggested that Mr Sunak’s statement may include a cut to fuel duty and changes to the threshold at which employees pay National Insurance, but it is expected to contain few other policy offerings and tax giveaways, as he attempts to shore up the public finances after the coronavirus pandemic.

“Every department that tried to put bids in has been quite harshly rebuffed,” said one disgruntled Whitehall source.

“If DCMS was asking about arts funding or whatever, that has been rebuffed.

“It’s not a Budget where everyone asks for bits and bobs, because there’s not really any money.”