The deal is likely to pass through the commons when it is brought to a vote on 30 December, with the Labour Party already having confirmed they will offer their support.
However the PM, who has previously seen his attempts to proceed with the substance of Brexit frustrated by his own party’s MPs, and has suffered a year of infighting on coronavirus legislation, has sought to reassure his own backbenches that the accord was the “right deal” for the country.
And having been able to appease a number of high-profile Brexiteers including Brexit Party leader Nigel Farage, the PM has made a particular effort to reach out to the Tory Eurosceptics whose support catapulted him into Downing Street.
In a WhatsApp message to his own MPs published in the Daily Telegraph, the prime minister acknowledged “the devil is in the detail” but insisted it would stand up to inspection from the European Research Group (ERG) of Brexiteers.
The influential group, which has attempted to steer the Brexit debate throughout the last five years, had vowed assemble a “Star Chamber” of lawyers to examine the 1,246-page text.
“I truly believe this is the right deal for the UK and the EU,” Mr Johnson reportedly told Tory MPs on WhatsApp.
“We have delivered on every one of our manifesto commitments: control of money, borders, laws, fish and all the rest.
“But even more important, I believe we now have a basis for long-term friendship and partnership with the EU as sovereign equals.”
He added: “I know the devil is in the detail” but the deal will survive “ruthless” scrutiny from the “star chamber legal eagles”.
Meanwhile writing in The Times Michael Gove, who was instrumental in the development of the deal, said it will create a new “special relationship” – a term usually used to refer to UK-US links – and end the “ugly” politics since the 2016 Brexit referendum.
On the other side of the channel the EU’s 27 member states have indicated they will formally back the deal agreed by the UK with Brussels’ officials within days.
The bloc’s ambassadors were briefed on the deal by Michel Barnier, who led Brussels’ negotiating team in the talks with the UK, on Christmas morning.
The meeting, which included at least one diplomat who wore a Santa hat for proceedings, concluded with ambassadors agreeing to write to the European parliament to say they intend to take a decision on the provisional application of the deal.
The European Commission has also announced a £4.5bn fund to help regions and industries within the bloc which will be hit by the UK’s withdrawal from the single market and customs union – including fishing communities who face losing out as the UK takes a greater share of stock in British waters.