Does anyone know the average tour length overseas for an NCO Aiman in early 1930s?

Trying to pin down the incident in which Sgt Charles Edward Slee parachuted on "August 24 1935 "

I am trying to find out what unit Slee was in at the time (to narrow down incident) and I have just found a passenger list travel record to Egypt for him on the Jervis Bay at Port Said in 1931 and was wondering if it was possible he would still be overseas at this time
Thanks
Paul