The U.K specialforces community both current and ex is composed of a comparitively small number of people,virtually all of whom who even if they do not actually know the person will almost certainly know someone who does.
B.G. companies and security companies operating in Iraq are usually run(though not always)by an ex and even if it isn’t will almost certainly have one or more members who are.
Being an ex is not an official secret though disclosing details of equipment,tactics,names of ex/colleagues or your “work history” is .
Most people try not to disclose it generally because it can make you and your family vulnerable to terrorists plus it can be a pain in normal life with wannabe hardmen wanting to fight you after they’ve imbibed some dutch courage,arse creeps sucking up to you and people operating under the impression that they somehow have the right to ask you intrusive questions about your present and past life or dictate how you behave.
ie.Well I always thought that you people should swim in the sea all year round/beat up my brother in law who I’ve had a row with/eat your steak raw. etc.
Fakes are ALWAYS found out, quite often within seconds of opening their mouths.