Boris Johnson has vowed to work “flat out” to deliver on his new Government’s priorities amid warnings that he is driving the country towards a no-deal Brexit.

Addressing the first meeting of the Cabinet since last week’s election victory, the Prime Minister said there would be no let-up in the “frenetic” pace, telling ministers: “You ain’t seen nothing yet, folks.”

His comments came as Downing Street disclosed that the Government is to legislate to prevent MPs extending the Brexit transition period beyond the end of 2020.

Ministers are re-working the Withdrawal Agreement Bill (WAB) – due to come before the Commons this week – to “legally prohibit” any further extension while talks on a free trade agreement continue.

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Cabinet meetingBoris Johnson addresses his first Cabinet meeting since the election (Matt Dunham/PA)

Opposition parties said the move was putting the UK on course for a “cliff-edge” no-deal break with the EU in just 12 months’ time.

Acting Liberal Democrat leader Sir Ed Davey said: “This Tory Government’s reckless approach to Brexit will send the country straight off the no-deal cliff.

“The only way Johnson can meet the December 2020 timetable is by giving up all his previous promises to Leave voters and agreeing to all the demands of the EU.”

Addressing Cabinet, Mr Johnson sought to drive home his message that the Government must now repay the trust of the voters who returned the Tories to power – many of them having voted Conservative for the first time in their lives.

“We should have absolutely no embarrassment about saying that we are a People’s Government and this is a People’s Cabinet, and we are going to be working to deliver on the priorities of the British people,” he said.

“That’s what they want us to do and we must recognise that people lent us their votes at this election.

“It was quite a seismic election but we need to repay their trust and work 24 hours a day, work flat out, to deliver on this.”

The PM’s official spokesman said ministers discussed the Withdrawal Agreement Bill, the Queen’s Speech and the latest employment statistics during the Cabinet meeting.

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Afterwards, Mr Johnson was congratulated on his election victory by European Commission president Ursula von der Leyen.

The pair agreed to work together with “great energy” to agree a future partnership by the end of next year, the spokesman said.

Under current plans, the Government intends to end Britain’s EU membership on January 31, with an implementation to run to the end of 2020 while it negotiates a free trade agreement with Brussels.

However, key EU figures – including chief negotiator Michel Barnier – have expressed scepticism that a deal can be agreed in time, raising the fresh prospect of a no-deal break unless there is an extension.

A Number 10 source said: “Last week the public voted for a government that would get Brexit done and move this country forward – and that’s exactly what we intend to do starting this week.

ToriesBoris Johnson with newly-elected Conservative MPs at the Houses of Parliament (Leon Neal/PA)

“Our manifesto made clear that we will not extend the implementation period and the new Withdrawal Agreement Bill will legally prohibit the Government agreeing to any extension.”

The Prime Minister repeatedly promised during the election campaign that he would not seek any extension to the transition period.

The commitment was instrumental in persuading Nigel Farage not to stand Brexit Party candidates in Conservative-held seats.

However, after Mr Johnson was returned with an unexpectedly large majority, there was speculation that he could use his strengthened position to seek an extension if more time was needed to get a trade deal.

The latest move would appear to have put paid to that.

The Withdrawal Agreement Bill is now due to be brought before the Commons on Friday – and could receive its first reading and be voted on at second reading in one day, if the Speaker agrees.

MPs were gathering at Westminster for the first sitting of the new Parliament with the re-election of Sir Lindsay Hoyle as Speaker expected to be a formality.

The rest of Tuesday and Wednesday will be taken up with the swearing-in of MPs, ahead of the State Opening and Queen’s Speech, which sets out the Government’s legislative programme, on Thursday.