The Tree shaped buildings
In response to SIRTOPPAMHATs picture, yes the ones at Wittering did contain 6 of these "dustbins" and were originally used to hold the Plutonium cores for the Red Beard 20Kt weapon, one in each bin.
The one I "owned" was used to hold the radioactive sources I used for calibration and testing of the radiation monitors. Some of them were rather hazardous and needed to be handled with a five foot pair of tongs before being deposited into a portable lead safe.
As each one had a manifoil combination lock on them which were renowned for being a right pain to use I once placed one of my sources on a spare desk in my secure office, locked the door, placed the appropriate hazard warning signs outside and went to lunch. Unfortunately one of my colleagues was on leave at the time and had unknown to me placed his filmbadge in the desk drawer. The first we knew of any problem was when Neddy was carted away to sick quarters a couple of weeks later when the badges were developed and his recorded a massive exposure.