Loop round the parimeter of RAF Brize Norton, to Black Bourton. Mainly roads and paths (Tarmac with a little compressed surfaces, but flat and even). From Black Bourton back to Carterton has a number of segments that are just on the road as no paths. Please ensure that you run facing oncoming traffic.
Lots of this are not lit and quite rural. Not suggested on evenings, though is possible with a head torch and good reflective clothing (if possible, with light bands on arms (and ankles)). Please make sure you can be seen