For the uninitiated, Parkrun sees people of all ages and abilities gather in an outdoor space at 09:00 on Saturdays and run for 5km – or just over three miles.
Shorter 2km runs for children aged four to 14 and their families take place on Sunday mornings.
By Christmas of 2004, the numbers had doubled and by the time of the 2012 Olympics the event had expanded to every London borough.
Last month, Lithuania became the latest country to host a Parkrun, taking the overall tally of nations to 23.
Ireland is the most popular place for Parkrun worldwide – where between 8-9% of the population are registered.
In London, where it all began, there are now nearly 750,000 registered parkrunners (including Greater London) and about 100 events each weekend.
