Thanks, unfortunately they don't really help. The quoted insurer's statement serves to confuse the issue even further:
We use the number of bedrooms to give an indication of the overall size of a house. For this purpose, a bedroom is defined as a room either originally designed for sleeping in (even if now used for other purposes), or later converted for sleeping in. For example, a bedroom used as a study counts as a bedroom. A house extended by converting the loft into a bedroom would increase its number of bedrooms. A bedroom converted into a bathroom would, under this definition, also count as a bedroom.
Why don't they just ask how big the house is, if that's the purpose of the 'number of bedrooms' question? Surely that would be easier and more accurate? As for knowing the original intended purpose of each room I suppose I could try hiring a medium to find out.
I did try to get a quote from first direct bank who were advertising 'unlimited rebuild cost' but after wasting half an hour on the phone they eventually admitted that it was limited (ok, to £1 million) but they still needed the actual rebuild cost because it affected the premium. In other words, their policy was not unlimited by either interpretation.
And finally, why on earth is any of this relevant? Surely the only things that are important when an insurer is establishing their liability when providing buildings insurance is the total rebuild cost and likelihood of damage occurring? How on earth could the number of rooms that happen to be called bedrooms or what I do for a living affect the cost of repairing or rebuilding my house?