Sun Who, sounds like the toaster I had modified at Wittering.
As you may know, Wittering is one of the oldest RAF messes. I was member and we had lots of electrical problems. Bar lights would last no more than 2-3 weeks. The industrial toaster would blow the fuses. PSA would . . . well not a lot.
I took the toaster down to workshops and they disconnected one element dropping it from 3300 watts to just under 3000; that did the trick.
In the Nimrod case it might have been power or maybe the offending slots were in the air path to the smoke detector?