Thanks folks, it's the aircraft logs (airframe, engine, propellor) that I'm interested in. Can someone point me at where it's stated that they can't be on board?
Ref other docs: there's a bit of misinformation in the replies. The ANO states: "If the flight is intended to begin and end at the same aerodrome and does not include passage over the territory of any country other than the United Kingdom, the documents may be kept at that aerodrome instead of being carried in the aircraft." See para 86 for more info.
HFD