RunThrough races are well organised, reasonably priced and friendly, with a number of different venues to choose from throughout the year.
The pre-race information is thorough and provided via email and social media well in advance, and on the day the team of marshals look after the runners very well.
The Wimbledon Common route is in 5k laps and you can choose on the day whether to run one or two laps. The course is flat and scenic, with a Womble thrown in for local interest :-D
The medals for RunThrough races are always well designed with fun themes around the venues, and the drinks and snacks you are provided with afterwards are generous, including their legendary flapjacks. It's well worth trying to fit at least a couple of their races into your calendar if you can.