cwatters
Airside is not a road or other public place, It can be for some offences inside the terminal, but by no stretch of the imagination are the aprons, stands, taxiways etc....
As regards to your quote from the Transport & Works Act. Can i suggest you read the act? Unless I have got it seriously wrong, it applies too, according to S26:
(a) a railway;
(b) a tramway;
(c) a system which uses another mode of guided transport and is specified for the purposes of this Chapter by an order made by the Secretary of State.
None of the above is gives powers airside at an airport.