London Marathon organisers to host COVID-19 test event for UK Government Monday, 5 April 2021 London Marathon Events (LME) is set to host the Reunion 10K as the UK Government aims to gather scientific data on holding mass participation events during the COVID-19 pandemic. The event on April 24 and 25 will be one of the pilots in the Events Research Programme, and is planned for Hatfield Park to the north of London. It will consist of three separate 10-kilometre races, held over the weekend. The format has been designed in cooperation with the Department for Digital, Media, Culture and Sport (DCMS), with the aim of understanding how mass participation events can go ahead as part of England's roadmap out of lockdown from June 21.