The possibility of holding the 2027 London Marathon across two days – Saturday and Sunday – is still being explored.
Brasher previously said the idea would be to hold the elite women’s race on one of the days, alongside other women to have gained entry through their previous marathon times – and wheelchair races.
The men’s equivalents would take place on the other day, with mass races across both days.
Speaking to BBC Breakfast on Tuesday, Brasher said he hoped it would be confirmed by the end of May.
“This is for one year only. We are engaging, and have been engaging for a long time, with a lot of stakeholders,” he said.
“Rightly, they want us to go through a process to ensure what we do is appropriate. People will get disrupted – it’s never happened before on a Saturday.
“There are lots of plans and mitigations that we’ve got and we would have do some unique things.
“But I think this shows the desire, the need, for the country. More than £400m of economic and social benefit would happen as a result of the two days, and we believe more than £150m would be raised for charities.
“It would be a one-off. We hope to get there – we’re not there yet. I’m positive it’s the right thing to do.”