As far as the UK CAA acceptance of these hours is concerned I know of lots of people who have done the flying, logged the time as P1 and the CAA have not pulled them up for it. I have heard second hand of people who have been pulled up for it and whose logged P1 time has been disallowed.
Pre JAR FCL, CAP 53 and 54 had a page that set out (fairly) clearly what you could count. At that stage one of the key features (as far as the CAA were conerned) was that only one pilot could claim P1 for a flight. I believe that under other "rulemakers" a number of pilots can claim P1 for a flight.
I wouldn't recommend asking the CAA directly cos you know what answer you will get - the one that makes it more expensive for you!