I believe this emblem came from the Joint Service Bomb Disposal School at Broadbridge Heath in West Sussex when they relocated the school in 1966. My father, who was in the US Army EOD, was stationed in the UK during the 60s and I’m guessing that’s where he got it. Measures about 3.75” (9.5 cm) in diameter and has a clear, slightly domed layer of resin over a metal base.