Probably because - under RAF rules - a the sleaves of a CS95 shirt can be worn rolled up but the sleeves of a PCS CU jacket cannot (with a minor exception). So airmen are correctly dressed (apart from the absence of TRFs), if the Air Chf Mshl turns up differently then would you tell him to change?
He heads Joint Forces Command, it is not unusual for the personal staff of senior officers in joint appointments to be from another Service.
Last edited by Climebear; 31st Oct 2012 at 16:28.