John McDonnell, the shadow chancellor, downplayed the scale of the changes needed for the Brexit plan

John McDonnell has suggested that Labour could sign up to large parts of Theresa May’s Brexit plan, saying they are realists and know they cannot “run in at the last minute and get it all”.

The shadow chancellor told Newsnight on BBC Two that Labour is all but certain not to support the prime minister’s deal if she concludes one on Sunday. However, he went out of his way to downplay the scale of the change needed to get its support and suggested that the party accepted the need for compromises.

Labour wants to keep Britain in a customs union, leave the single market but maintain a “strong single market relationship”, end free movement and change state aid rules.

Mr McDonnell said: “We’re not talking