As he was pushing the Greens commitment to housing, the Labour Party was questioning it.
Outside the building where the launch was taking place, a van pulled up.
On it, claims from Labour that across the country the Greens had blocked the development of more than 40,000 homes.
Housing Secretary Steve Reed said: “Zack Polanski can launch whatever campaign he likes, but the facts don’t change.
“From Lewisham to Camden, Hackney to Islington, Greens have opposed thousands of homes in a city where the housing crisis is most acute.”
However, Polanksi hit back.
“I think Labour saying they’ve done some research is doing some heavy lifting there because no one seems to know where these numbers have come from,” he said.
Polanski added that Green councils across the country had given planning permission for new homes, but accused developers of failing to build.
When asked if he thought voters were turning to the Greens because they liked their policies, or were just fed up with the other parties he replied: “Honestly, it’s probably a bit of both.
“It excites me as a Londoner to know that there is an option on the ballot paper that will excite people and bring communities together – that looks like the future of London.”
On 8 May we’ll know how many Londoners agree.
