Colin Wilson wrote:
There used to be sawdust under it

I was boarding our loft recently, and there was a load of sawdust
under where the tank used to be (which had been removed long before I
bought the house 20 years ago)

If I might be so rude as to enquire, when was the house built and what area
of the country? As you might appreciate from my other posts, I've just
become curious about this!