Hi Brian,
Colin Campbell McMullen 32118, an Australian in the RAF
Biographical details here
http://www.rafweb.org/Biographies/McMullen.htm
Not sure if the 201 Sqn listing is correct - in June of 1934 McMullen was posted to 203 Sqn RAF at Basrah, Iraq and left in Mar 35.
McMullen studied Veterinary Science at Sydney University and was also a Rugby player with University and Drummoyne Clubs. Along with another Australian W.J. Hickey (32035) they resigned from the Citizen Air Force in Nov 1931 and I think both attended 3 FTS at Grantham from the 17th. I have a note they were posted to 1 Sqn RAF prior to 43 Sqn RAF (17 Mar 32) but have not checked.
Regards, Drew