Let me guess. Nuclear waste?
The short list made by Nirex for nuclear waste sites in the the late 1980s was revealed in 2005. Some may still be on it.
Adjacent to Bradwell nuclear power station in Essex
Ministry of Defence land on Potton Island, 8 km from Southend on Sea. Essex
Under the North Sea, accessed from the port at Redcar, Yorkshire
Under the sea between the Inner Hebrides and Northern Ireland, accessed from the port at Hunterston in North Ayrshire
Killingholme, South Humberside
Ministry of Defence training area, Stanford, Norfolk
Adjacent to Dounreay nuclear plant in Caithness
Two sites near the Sellafield nuclear plant in Cumbria
Altnabreac in Caithness 18 km south of Dounreay
Fuday, small, uninhabited island north of Barra in the Western Isles
Sandray, small, uninhabited island south of Barra in the Western Isles
The past is a foreign country: they do things differently there.