RAF man the aircraft that taxi around the UKSF so I suppose this would be their equivalent of 'Special Forces'. I read somewhere on here that the RAF Regiment help man the SFSG, and also carry out combat search and rescue, that might qualify as SF, I'm not sure.
The RN are involved with the SBS I believe as RN & RM are linked up in the same organisation. There are also have clearance divers who have a v physically demanding course to pass, and Royal Naval Commandos, who are sailors who've had to pass the Commando Course to support the Commando Brigade. Again I'm not sure if these last examples are considered SF or not, but theres certainly the scope to do something physically demanding if you're not in the Army/RM.
Edited to add: Or have I just fallen prey to my first WAH?
