There's a room full of CAA legal bods looking at this area of the ANO. Trouble is, they are powerless to do anything until the JAR/EASA/Whatever body sorts itself out.
I would say that the pilot you hire must ask some pertinent questions about the flight(s). He is, in law, the Commander and responsible for everything that happens in flight.
So - he has an ass and a hard-earned license to protect.
We all know that there are a load of UK-based N machines doing dodgy stuff without an AOC, we all know that some of them are doing illegal aerial work - and we all know that there are a number of PPLs out there who are employed as butlers by wealthy owners.
As ever, all fine until the ship hits the fan.