Soprry to resurrect and old threat, but worth looking at Clapham Pioneers, a running club based in Clapham Common. They are based in Wingate Square near the tube station, and run Tues nights and Saturday mornings. Tuesday nights there is a longer run (6-8 milesd) a 5k run, and an interval session. A very friendly bunch, always a few beers in the Calf Pub afterwards on Tuesdays. There are people there from sub 3hr marathon runners, and people who do the 5km route in 30 minutes.
there is a new small running club that goes from Pioneers running shop in Clapham Old Town. The runs tend to be around 10k, but it's very friendly and lots of people running at different paces. Google the shop, give them a call, and ask to speak to Leigh..