London Marathon 2025: route, runners and everything else you need to know

With London’s temperatures forecast to rise into the low 20s, the conditions could prove challenging for many even over a route that is mostly flat. Composite: PA/Getty/Action Images

The 45th running of the London Marathon gets under way in Greenwich on Sunday morning, a diverse multitude of elite athletes, costumed fun-runners, wheelchair competitors, the capital’s streets thronging with supporters over 26.2 miles, all cheering home the biggest field – 56,000 souls – to take part in this celebrated event.

Central London’s traffic may grind to a halt but records will fall, personal landmarks set and colossal sums of money raised for charities. The race is, after all, the world’s largest annual one-day fundraising event, with more than £1.3bn raised since 1981. And whether you are competing or following the action, here is your guide to the day …