My bold:

Club Membership is open to all persons who hold, or have held, a Commission in the Royal Air Force, Princess Mary’s Royal Air Force Nursing Service, The Reserves, The Auxiliaries and in Commonwealth and friendly Air Forces.

Spouses of Full Members can also enjoy Associate Membership and make full use of the Club’s facilities.

http://www.rafclub.org.uk/home/club-and-contacts/raf-club-history

So commissioned officers and spouses.