Britain needs to accept it is no longer a first-rate global power, former prime minister Sir John Major has declared.

In a speech in London last night, Sir John said: 'We are no longer a great power. We will never be so again... 

'We are a top second-rank power but, over the next half century – however well we perform – our small size and population makes it likely we will be passed by the growth of other, far larger, countries.'

The former Tory leader claimed that the result of Brexit trade talks will be 'a flimsy, barebones deal or no deal at all', which he described as a 'wretched betrayal of what our electors were led to believe'.

'It now seems that on January 1 next year, Brexit may be even more brutal than anyone expected,' he added.

'Because of our bombast, our blustering, our threats and our inflexibility – our trade will be less profitable, our Treasury poorer, our jobs fewer, and our future less prosperous.'

And Sir John warned that one 'deeply troubling effect' of Brexit is the 'risk of breaking up the UK by increased support for Scotland to leave the Union, and Northern Ireland to unite with the South'.

He put forward a suggestion that ministers should agree to a Scottish independence referendum only on the basis that if there was a vote to leave the UK there would need to be a confirmatory referendum following divorce talks.