Riverdale / Belfast.
(Gleann na hAbhainn) / Belfast.
The post office opened in 1964-9. It has previously listed an english SRDS and Parcel Mark.
Riverdale / Belfast 11
Earliest known date - 24 Jun 1966
Latest known date - 24 Jun 1966
Postmark type - Circular, Single Ring, No Time Code, date on two lines as DD MM / YY.