Captain S - I cannot see where your reference to 'exceptional circumstances' is coming from? Have a re-read of the CAP quote!
What I am trying to raise the profile of here is that CAP371 gives ANY UK AOC holder the 'right' to roster crews (when 'hoteled' by the company) for a minimun of 10 hrs 'at the hotel'.
No exceptional circumstances, no 'Captain's Discretion' (although he may decide it is NOT safe, of course, with the associated risks of disciplinary action (vis AL), no 'occasional', no 'when necessary'. Just 'MAY BE'.
I should point out that it cannot be done (on UK rules) on an 'at home' rest period other than by the 'Captain's Discretion'.
The point is, do the public think that a 12 hour duty day (eg start at 0600, finish at 1800) can safely be followed by 10 hours rest at a hotel, with food and relaxation to find, as well as pack/unpack, possibly also arrangements to make for the next day, followed by get-up at 0500 to report for duty at 0600 the next day, possibly for the same?