ANO Article 259
(1) Subject to paragraph (2) and Part 34, aerial work means any purpose, other than commercial air transport or public transport, for which an aircraft is flown if valuable consideration is given or promised for the flight or the purpose of the flight.
(2) If the only such valuable consideration consists of remuneration for the services of the pilot the flight is deemed to be a private flight for the purposes of Part 3 and Part 4.
(3) Aerial work consists of instruction or testing in a club environment if it consists of the giving of instruction in flying or the conducting of flying tests for the purposes of this Order in an aircraft owned by, operated by or operated under arrangements entered into by a flying club of which the person giving the instruction or conducting the test and the person receiving the instruction or undergoing the test are both members.
It is rather annoying when CAA inspectors make up their own rules - unfortunately, it happens all the time.