There was a chap, who had supposedly found the site, where the metal had been collected during the WW2 scrap/salvage propoganda campaign, and buried somehwere on Dartmoor. This could feasibly have the WW1 tank which was on a plinth in Millbay, near the park. Although the whole would be a pile of rust by now.
Plenty of rumours of kit buried around Slapton, including bodies after the ill-fated Op. Tiger.