WRT 'holes in the ground'; at the risk of thread creep:
My 2 i/c at Marlow ATC was an erk in the late 50's early 60's. He was posted to North Coates to re-open the station when it was selected as a Bloodhound site. An SNCO took him and others to a locked Robin hangar to see what was in it; on cutting off the padlock, they found it was stacked full of Beaufighter toolkits*. As they were not in the inventory and thus would need to be 'explained', the SNCO told the erks to dig a hole and bury them!
*I was told 'toolkits' but did toolkits for specific types exist? Could he have meant spareskits?