I’m the co-founder (with Brooner) and race director (2008-13) of the London City Race, one of the world’s largest standalone urban orienteering events, organised by South London Orienteers and taking place annually in September with around 1000 participants. The first event was in 2008 as the City of London Race. After five years in the City, the race was held in Canary Wharf and on the Isle of Dogs, in 2013, on a brand new orienteering map.
The current race director (2014-) is Vince Roper, contact him at cityrace (@) slow.org.uk. The 2016 race takes place on Saturday 10 September.
The City Race website, which I still administer, is here.