Sir Keir Starmer has said he would be “chucked out” of the Commons if he took his personality from the football pitch into Parliament.
He also said he’d “probably knock over” the Prime Minister if he was on the pitch with him.
In a wide-ranging interview with Piers Morgan for Piers Morgan’s Life Stories, the Labour leader spoke about his childhood, the death of his mother and his strained relationship with his father – where he pledged to be “different” with his kids.
Politically, he believes now is a “pivotal moment” for both him personally and his party.
Mr Morgan told Sir Keir, in an episode of Life Stories aired on Tuesday night, that his friends described him as “loud” and “garrulous” and that he was “a guy who plays football every Sunday and kicks seven bells out of people, beating his chest like he’s Patrick Vieira”.
But Sir Keir said: “There’s a big difference between the forensic lawyer and Keir on the football pitch. If I was Keir on the football pitch, I think I’d be chucked out by the Speaker. So we’ve got to be careful about how far we go.”
He said: “Let me get out there, let me take the mask off, because we’ve been living in restrictions.
“As we come out of this, this allows the space to open up, the pandemic allows the political space to open up, the restrictions allow me to open up.”
Asked what he would say to Boris Johnson right now, he said: “Move over, we’re coming.”
And when asked what he would say to the Prime Minister on the football pitch, he responded: “I’d probably knock him over.”
On Labour’s prospects, Sir Keir acknowledged the “hurtful loss” in Hartlepool, saying: “I’m not going to pretend the last few weeks have been easy, but there’s a huge emotion that runs through the Labour Party, and we lost in Hartlepool, we lost badly.
“But when you want to win, it hurts to lose. There’s emotion there.”
He said his three top priorities were a “first-class education for every child. Second thing, to make sure our economy deals with insecurity and inequality. A third thing is to put real dignity into older age”.
He added: “The biggest change we need to make is a Labour Party that stops looking in on itself and looks out to the electorate, to the voters.”
Sir Keir said already he was proud of his work to eradicate anti-Semitism from the party.
“We had to make changes, so on things like anti-Semitism, it was really important to me and to the party, I think, to the country, that we dealt with anti-Semitism,” he said.
“We’ve begun to do that, taken some really, really important steps. We’re turning the party around.”
When probed several times by Mr Morgan on whether he had ever taken drugs, Sir Keir refused to respond, saying: “I spent my university days in the library.”
Asked whether he really spent all his time studying, he said: “No, we had a good time. We had a good time. We went to bars, went to gigs. We worked hard, we played hard.”
In his personal life, Sir Keir said it was one of his big regrets that his mother could not see him elected as an MP.
His mother, Josephine, died just two weeks before he was elected for Holborn and St Pancras in 2015, and he described the difficulty she faced living with Still’s disease – an incurable autoimmune condition.