The London Marathon has confirmed that next year’s race will be staged over two days to enable a record 100,000 runners to take part and raise tens of millions more for charity.

That will be welcome news for the 1.3 million people who have applied through the ballot, although their chances of getting a place on the start line will still be considerably less than 10%.

The Guardian exclusively revealed in March that advanced talks were under way to hold what organisers have called “the Double” on Saturday 24 and Sunday 25 April 2027, with the event crucially getting the early backing of the London mayor’s office. However, it took longer than expected to get every stakeholder on board, with Transport for London and others expressing reservations about shutting down the capital for two consecutive days.

But the idea of a one-off event, that would not only be the biggest marathon in history but raise a record £150m for charity, eventually proved irresistible and the news was confirmed by the London Marathon chief executive, Hugh Brasher.

“The 2027 TCS London Marathon Double is our most ambitious evolution to date – a once-in-a-generation one-time-only reimagining of what a marathon and city-wide celebration of activity can be,” he said. “By expanding to 100,000 runners across two days, we’re opening the door for more people, more charities and more communities to take part in the world’s greatest marathon. We believe that more than £150m can be raised for good causes and the UK economy will have a £400m social and economic benefit.”

Organisers also confirmed the Guardian’s reporting that the elite women, elite female para-athletes, championship and “good for age” women will run on the same day alongside a mixed mass event with close to 50,000 runners.

The elite men will then headline a similar programme on the other day, which will also include a second mass participation event. Those waiting to hear whether they have a ballot entry will be told in early July. However, organisers have confirmed that runners will not be allowed to take part in the in-person event on both days.

The two-day marathon was also welcomed by the London mayor, Sadiq Khan. “London is the sporting capital of the world and I am delighted that, for one year only in 2027, the world famous TCS London Marathon will expand into a two-day event,” he said.…

“This unique, one-off double will allow a record 100,000 participants to take part across the two days – creating the largest fundraising moment in UK sporting history and supporting the work of so many incredible charities.”