Boris Johnson and David Cameron
Boris Johnson and David Cameron are not on the same page over the EU negotiations Getty

David Cameron took on Boris Johnson in front of MPs just a day after the Mayor of London revealed he had "doubts" about the draft EU reform deal. The prime minister acknowledged on 3 February that the settlement from European Council President Donald Tusk was imperfect.

But the Conservative leader argued the UK's relationship with the 28-nation bloc would be stronger due to his renegotiation with Brussels. "I am not saying this is perfect, I am not saying the EU will be perfect after this deal, it certainly won't, but will the British position be stronger and better? Yes it will," Cameron claimed.

It came after Johnson, who is tipped as a future Tory leadership contender, queried if the changes laid out in Tusk's document would "restrict the volume of legislation coming from Brussels". The grilling also followed the Uxbridge and South Ruislip MP's admission to LBC Radio that he had "doubts" over the "red card" proposal from the EU.

The measure would enable member states to block new legislation from Brussels so long as a majority of parliaments voted against the draft law(s). "We will have to see how it is explained to us, I haven't yet got a firm view on it. I have doubts," Johnson said.

Alan Johnson, the leader of Labour In, also used the session after Cameron's statement on the draft EU deal to tease the Mayor of London. The former home secretary noted Boris's father, Stanley, is the co-chair of the new pro-EU Environmentalists for Europe campaign.

He said: "Will [the prime minister] also welcome the splendid article last week setting out the importance for science and technology of remaining in the EU, penned by his science minister [Jo Johnson], the brother for the Member for Uxbridge and South Ruislip?

"Will he have a word with his Right Honourable Friend and tell him the importance of family solidarity in joining the swelling ranks of Johnsons for Europe."

Cameron agreed with the former home secretary and quipped that he would also "go after" Rachel Johnson, Boris's journalist sister. The Mayor of London is often billed as a Eurosceptic but he is yet to come out for either the "leave" or "remain" campaign.

The exchange came after Jeremy Corbyn claimed Cameron was "disrespectful" for not issuing his EU statement to parliament sooner. The prime minister said he wanted to give MPs a day to read and reflect on the settlement.

The Labour leader also described Cameron's renegotiation with the EU as "smoke and mirrors" and warned the deal, which includes a so-called "emergency break" on access to in-work-benefits, would curb workers' rights.

The draft deal means the EU referendum is expected in June but the Welsh and Scottish government leaders have urged Cameron to hold the ballot later in 2016 because of the 5 May votes. The latest opinion poll from YouGov, of more than 1,700 people between 27 and 28 January, put "leave" on 42%, "remain" on 38% and "undecided" on 20%.