Homeless Londoners face a new crisis.

In the first lockdown, by acting quickly, many lives were undoubtedly saved through the “everyone in” policy. Infections were low and people got the help they deserved, which they had struggled to find in normal times.

There should be no delay in reinstating that support scheme now, but London also needs long-term ideas to make sure everyone has secure homes beyond the pandemic. I have discovered in my work scrutinising the mayor’s budget, that he is sitting on more than half a billion pounds - £535 million - in capital funding for new affordable homes, which forms part of his multi-billion pound grants programme but has not yet been allocated to any scheme.

In a recent City Hall budget meeting, I asked him about this. Initially he did not accept there was any money “spare” but the GLA has now confirmed in response to Inside Housing that this amount does indeed remain unallocated.

At the meeting I proposed the mayor could, within the terms of government funding, actually buy up market and shared ownership homes that are already built or near completion. There are many, many homes that could become real new council homes this way. In some cases they could be occupied practically within weeks, providing help for people in need now, with a clear long-term value for money case in the context of a health and growing housing crisis.

I already wrote to the mayor’s team in April asking them to find options for unoccupied homes. My suggestion then was for unoccupied or unsold homes to be rented and used, either as temporary accommodation for those in housing need, or as more permanent affordable rented homes. This newly discovered funding pot would be a way to make these ideas possible at scale and permanently, by buying the homes instead.

I would like to see an urgent action plan to use the unallocated funds as soon as possible. This money is no use in London’s back pocket. If we’ve got more than half a billion pounds that we could use, why would we not do this now today?

• Sian Berry is councillor for Highgate ward, member of the London Assembly and Green Party co-leader.