I don't understand why the RAF continue to insist that pilots log flying hours this way. The actual flight time recorded in the F700 is used for engineering purposes and some sqns also derive stats from auth sheet entries. However, I see no reason why chock-to-chock times shouldn't be recorded in log books, giving the pilot due credit for being in charge of an ac moving under it's own power. As far as I'm aware no-one then subsequently cross refers to log books to produce any other stats - do they? If necessary, one of the spare columns on the auth sheet could be used to record chock-to-chock times for audit purpose, or we could simply adopt the CAA credit for each flight when completing the log book.
Whilst this topic is trivial in isolation, it is perhaps symptomatic of a wider issue. We have several out-of-step practices, such as RT and altimeter setting, that do have their own merits but start to look decidedly anachronistic as we become a relatively smaller player. I firmly believe that adoption of common practices carries greater benefit than the minor irritation of getting used to doing things everyone else's way and, except where absolutely necessary, we should swim with the tide.