Operation Cauldron

Operation cauldron' was a secret government operation where in 1952, on a floating pontoon off the coast of Tolsta, Isle of Lewis, animals were tested with biological agents.

The pontoon was supported by another vessel the 'Ben Lomond', and some 3,492 guinea pigs and 83 monkeys were tested on. In an interesting development, a crewed ship, an English trawler called 'Carella', ignored warnings to stay out of the area when tests were being performed and instead sailed through a cloud of bacteria on return from a fishing trip to Iceland.

The ship was then closely and importantly secretly monitored by a destroyer and fisheries vessel for 21 days to see if any medical emergencies were reported via the radio. This surveillance even included a period where the crew mingled with residents in Fleetwood when the ship docked there for shore-leave. The tests were announced a failure and all records were subsequently destroyed.

A novel, 'In a Veil of Mist' was released in 2021 by Lewis author D.S. Murray on the subject of this event.

More information on visiting the area can be found here.