Iran was a member of CENTO up to its demise in as a consequence of the Iranian revolution and the Turkish invasion of Cyprus.
(I was in Cyprus in 76-78 (when we were ordered to destroy all our CENTO documents) and I went as a NATO observer at a CENTO exercise in Diyarbakir*. Fond memories of the Iranian and Pakistani observers, always wondered what happened to the Iranians.
The Vulcan squadrons at Akrotiri, 9 and 35, were assigned to NEAF and the CENTO nuclear role until the Turkish invasion and their withdrawal in 1975.
Not sure how many RAF personnel were permanently based in country in CENTO roles prior to its demise, but you will find stories on pprune of crews recalling their flights, night stops in Teheran in transit to the Far East and return along with other stories.**
*
Taceval, Maxival and Minival
**
Did You Fly The Vulcan?? (Merged)