Hollywood actress Carey Mulligan and Olympian and British sprinter Adam Gemili are taking part in the Run to the Beat half marathon.
The race powered by Nike+ is London's biggest half marathon, with 19,000 runners set to make their way around the 13.1 mile course.
It starts and finishes in Greenwich Park.
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A police officer who spent six days crawling the London Marathon in a gorilla costume has finally completed the 26-mile route.
The victim of a "violent and sustained attack" on the top deck of a London bus has been named as Archie Sheppard.
Transport for London has made the badges and accompanying cards permanently available after a successful trial in autumn last year.