Theresa May has “reached the point of no return” with her Brexit deal and should resign, a senior Tory has said.

Former shadow minister Sir Bill Cash told ministers that Mrs May’s decision to postpone the meaningful vote on her Brexit deal was “contemptible” and had led to “public trust being shattered in our democracy”.

Sir Bill, who is a staunch Brexiteer, dismissed Mrs May’s last ditch attempt to get concessions from the EU, saying “secret room” deals would not cut it.

He said: “The Prime Minister has now reached the cliff edge of resignation, I believe that she may well have to resign, and yesterday’s events and running away from the vote and then off to Germany, Holland and the EU, was yet another a humiliation for the United Kingdom, she is clinging to the wreckage, she has reached the point of no return.

“The pulling of the vote yesterday was an insult to the House of Commons and was admission of the failure of the withdrawal agreement itself.

“It magnifies the contempt of the House displayed in respect of the Attorney General’s opinion, which in itself remains incomplete.”

He added: “Further discussion on the backstop in the secret rooms of Holland and Germany and Brussels will not resolve these questions.

“I would simply say as I conclude, I call to mind John of Gaunt’s famous speech in which he declared that with ‘rotten parchment bombs this country hath made a shameful conquest of itself’, this withdrawal agreement does just that.

“It is a breach of trust, it is a betrayal, this clutching of straws – this running away from the vote is contemptible.”

Tory Brexiteer Nadine Dorries later likened Mrs May to Adolf Hitler in his bunker at the end of the Second World War.

The Mid Bedfordshire MP said: “The Prime Minister I think is being very badly advised by third-rate advisers in Number 10.

“I saw our Whips office being criticised in the papers today but it’s got nothing to do with them, they are also having to deal through the same third-rate advisers.”

On the failure to put the Brexit deal to a vote she compared Mrs May with the Nazi leader in the film Downfall, which shows him commit suicide as Germany is defeated.

Ms Dorries said: “The Prime Minister is in a bunker, she’s starring in her own episode of Downfall, and we all know how that story ends.”