It was a nice relaxed explore with some good photo opportunities.
A little history (from wikipedia):
Bodney was established in 1940 as a satellite field for RAF Watton. The airfield was grass-surfaced and located on slightly rolling land with a hard surface perimeter track.
It was used by the RAF for a short time then the USAF.
With the end of military control, Bodney airfield was closed and was returned to agriculture in November 1945. Almost the entire facility was completely reverted to farmland, although a few derelict buildings remain as well as its control tower.
More info here
I think this ammo is from recent training exercises