Casevac Protocols to ensure secrecy
The numbers of SAS who were injured in Op STORM and required casevac to the UK were assessed to be small. It was unlikely that more than one at a time would need  Casevac by the RAF and therefore it was proposed that they would be put on flights that contained other passengers. If the plane was full some of the other passengers would be off loaded. The patient along with bits of medical kit and flight attendants was going to take some explaining away yet the aircrew were required to say nothing.
The Documents above are from the PRO at Kew and are reproduced under the OGL conditions. relating to Crown Copyright