It was the latter, civvies from Peterborough.
The guards were not used because the Station Commander said something about..."I'm not having some airman shooting up my airfield."
Yes that was it.
The farmer and his son dragged the cow (with our help) up the ramp and took it away, so no free beef was obtained.
I remember the son put his finger into the bullet hole, (much to our astonishment) and said "Look 'ere faaaaaather," Roight in 'is brains."
Fond memories!