Perhaps the most interesting sub-plot to Labour's first London mayoral hustings involved two people who weren't in the room: Ed Miliband and Zac Goldsmith.
It's de rigueur for Labour politicians to put as much distance between themselves and their unfortunate former leader, and the "mansion tax" is the most obvious stick to beat him with if you represent the capital.
Few on the panel actually disagreed with the notion of asking the better off to pay a little more. But the way the policy was framed, argued Tessa Jowell, created an "anxiety" among voters at a time when distrust still envelops politicians - tax the rich and the rest will be next, people felt.
It was David Lammy who went for the jugular. Underlining the fact the five contenders would make unlikely tennis partners, the Tottenham MP jabbed at Sadiq Khan over an apparent U-turn on Heathrow airport expansion.
"Zac Goldsmith announced he was running and suddenly Sadiq is against it. I think it is important to be straight with people, and not be playing the same Ed Miliband politics that got us nowhere," he said.
So "Ed Miliband politics" as a political insult. "Hell, yes" feels like a long time ago.
Zac Goldsmith, the mega-rich Tory MP who is asking his constituents for permission to stand, loomed large.
Christian Wolmar, the transport writer turned politician, opened by telling the audience he could "beat Zac". Gareth Thomas noted how his general election wins in Harrow were against "Zac Goldsmith's party". At one point he was referred to as "blonde and glamorous". The man isn't officially in the race but clearly Labour is already spooked, underlined by an Evening Standard poll hours earlier suggesting only Ms Jowell could beat him.
The mayoral contest is bigger than London for Labour, and there are parallels to the Conservative Party when they were on their uppers. Boris Johnson's defeat of Ken Livingstone in 2008 was vital to show the Tories could win again. It was supposed to be the springboard for a general election victory in 2010, which fell short but arguably paved the way for this May's unexpected triumph.
Labour needing to show it can win again is not the only lesson from recent history.
The capital likes independent spirits - see Ken and Boris. Phil Collins, the Times columnist and former Labour speechwriter who chaired the night, was right about the calibre of Labour's candidates, boasting top-ranking ministers and some of the party's best known names. Big beasts with potential to reach parts many politicians don't. But the Ed and Zac references suggest a lack of self-confidence in the Labour brand (this was the week of the "New Labour Taliban" comment) that they need to reconcile themselves with and quickly. The Conservatives won't waste time on an existential crisis.
Labour's mayoral candidates
Diane Abbott, MP for Hackney North and Stoke Newington, former health minister
Tessa Jowell, former MP for Dulwich and West Norwood, former culture secretary and Olympics minister
Sadiq Khan, MP for Tooting, former transport minister, shadow minister for London
David Lammy, MP for Tottenham, former minister for universities and skills
Gareth Thomas, MP for Harrow West, former international development minister
Christian Wolmar, journalist and author specialising in transport issues