The former Lord Chancellor Lord Falconer joins me for lunch, where we chew over the fate of the Labour party and his battle to lose weight.
We're squashed into the corner of rather a noisy café and he is munching his way through a couple of apples washed down with Diet Coke. Not the most indulgent lunch.
He has been on a diet for more than four years and has lost a great deal of weight.
Something I want to ask him about after the politics.
"I'm trying to be composed," Lord Falconer tells me. "But I feel very, very anxious about it."
The former Lord Chancellor is talking about the two recent by-elections, Stoke and Copeland. Both were Labour seats, Stoke they won, Copeland they lost to the Conservatives.
"Does it wake you up at night?" I ask him, "Yeah, It does".
He is relieved that they beat UKIP in Stoke but believes UKIP are in decline and worries about which party their supporters will turn to.
"A Copeland has never happened in my political lifetime. Copeland is basically a Labour seat, it's been a Labour seat for ever and ever and ever.
"It's not because what we are saying is wrong. For example, on anti-austerity we're in the right place. It's that our voices are drowned out."
Until last June he was shadow Lord Chancellor but resigned in the post-Brexit Labour meltdown, along with many of his colleagues.
Back then he called for the Labour leader to quit, now he is solidly behind Jeremy Corbyn, but says that they now need to concentrate on Labour policies, such as immigration.
"It's got to be clear that the Labour party has a clear and identifiable policy on immigration which recognises our obligation as a national UK party to promote the economic interests of the UK population.
"And that means restricting immigration from the EU, just as we restrict immigration from the non-EU."
Blair on Brexit
The former Labour Prime Minister Tony Blair, a close friend of Lord Falconer's, recently called for people to rise up against Brexit.
It was a speech which the Shadow Chancellor John McDonnell was not best pleased with. He wrote that a "soft coup" was underway, which involved elements inside the Labour party and the Murdoch media empire trying to undermine Jeremy Corbyn.
I ask Lord Falconer about it. He is hesitant at first.
"I don't know, I mean we've got to just work together to make progress in relation to all of this.
"I can't explain it to you. Unity in relation to what the party is offering is really important, it doesn't mean that people can't express views about particular policy areas.
"I think it's wrong to say that an ex-prime minister expressing a view about Brexit is part of something else. Let's not go there.
"We've got to have a message that we all share, that we all talk about."
We order our pudding, for me a banana, for Lord Falconer yet another apple.
He sticks to his diet with the single minded determination of someone who is terrified of returning to his previous 16 stone. He is now under 12 stone.
"It's a stunning change. I was completely defeatist about the whole thing. I was obviously a fat person in my 60s. The best I could hope for was gradually creeping up to 20 stone in my 70s.
"But I feel so much better, I feel so much more confident."
He is clearly delighted. His diet consists of eating only apples and drinking Diet Coke during the day and eating whatever he likes in the evening.
He says his constant anxiety of returning to his former larger self keeps him going on the diet.
"I've got to keep on getting below 12 stone all the time. My family think I am mad."
I ask him if he is becoming obsessive.
"I am obsessive about it. If I have a big meal in the evening I think, 'God, I'm really fat.'"
"I don't think I am anorexic, but unless I remain anxious about the weight being put on, how will I not just start eating again? Because I like eating."
I ask him if his wife worries about him going too far.
"Yes she does, but this current equilibrium is where we have got to," he says.
Before he goes I ask him about his other anxiety - the future of the Labour party. Does he worry they might not get into power again?
"I do feel so strongly, we've got to back in. We've got to get back in. We've got to really try.
"I worry profoundly about what will happen if Labour does not get back in. I've seen that we're between 14 and 18 percentage points behind in some polls and that doesn't feel like we are standing on the verge of power at the moment."
Becky Milligan's series of interviews with politicians, At Lunch With... is available as a podcast.