"This Labour party cannot and must not split. That is what many on the hard left of the party would quite like to see," he says. "I am deeply opposed to it because I think it hands the power in this country to the forces of conservatism indefinitely.

"I think you have to stay and fight for what you believe in. When I look at the colossal figures who inspire me in politics, the Mandelas, the Martin Luther Kings, the Keir Hardies, they faced much bigger obstacles to realising their values than even we face now in the Labour party. They wouldn’t have walked away and sought to split in these circumstances and we shouldn’t have any intention of doing so either."

Those who would like to see him return to the front bench to demonstrate this unity, however, will be sorely disappointed. In the event that Corbyn remains leader, Umunna will stay on the back benches. "I always said, when it was mutually agreed between me and Jeremy, that it probably wouldn’t be the best idea for me to be in his shadow cabinet, that it wasn’t the only way to contribute," he says. "I think there are lots of ways to make an impact."

And he's convinced that Labour isn't the only political party facing an identity crisis. "Viewed from the position of a Labour member, you could be very gloomy about this but this is a crisis and a challenge for all of mainstream politics across the advanced world," he says.

"The Tories have been given a false sense of security in my view because they are a government which was elected with the support of less than 25% of registered electors and have a prime minister which has no mandate.

"And how you deliver your values in the context of the big global forces knocking people around – the threat of global terror, the climate change catastrophe, the inequalities that globalisation throws up – they have all of this coming down the road and it may not come for a while but they’re going to have to deal with the same issues."

Umunna campaigned across England for the Remain campaign but says he knew the week before the referendum that "we'd lost it". He says it was immigration that most motivated people to back Leave, particularly in Labour constituencies, as well as the "chance to give the establishment a good kicking".

As he speaks to us on Wednesday, Theresa May has gathered her cabinet in Chequers to brainstorm ideas for exactly how Britain will exit the EU. More than two months have passed since the 23 June referendum, which saw voters back Brexit by 52% to 48%.

