The airfield event you refer to is at Long Marston - about 5 miles SW of Stratford. I've done it a couple of times. It is a completely flat course on airfield runways. One lap is 5k. It's grown a bit and I think they have about 800 entries across the four races. Course is dull but not as bad as you'd expect as you go past 'the pits' where the spectators gather once per lap, and there is a mix of everything from fancy dress fun runners to elite athletes there for a training workout. Parking and toilet/changing facilities are good. Great pb potential if it's a nice day but a bit not if it's wet and windy.
It is well organised and fast. Excellent changing facilities. Two laps of the GP circuit, and you get a split time as well. Not sure about medals. As it's very open, times can be affected by the elements. Last year was cold, wet and windy.