Page 247 - The Postal Agencies in Eastern Arabia

This was the first issue for which a special first day cancellation,
on the British pattern, was provided. It was a 38mm single-circle
inscribed “FIRST DAY OF ISSUE/ABU DHABI, TRUCIAL STATES”
and it was used for subsequent new issues until 1970 when a 26mm
single circle inscribed “FIRST DAY OF ISSUE/ABU DHABI”
replaced it.

Abu Dhabi definitives postmarked “Bahrain” on January 6th,
1966, the only day that official use of the cancellation
occurred.
The Abu Dhabi definitives may occasionally be found with
Bahrain cancellations (Type 21 or 40) on mail from Das Island in
1965-66. Such postmarking was almost certainly inadvertent, with the
sole exception of January 6th, 1966, on which day the Das Island Post
Office, together with its cancellers, was transferred from Bahrain to the
island. The mail which had been sent over to Bahrain that morning
before the Das Island cancellers arrived on the island could only be
date-stamped in Bahrain with a BAHRAIN canceller.
When the Das Island Post Office was transferred to the island it
was initially operated by A.D.M.A. on behalf of the British Postal
Agencies in the same manner as Awali P.O. in Bahrain and Ahmadi
and Mina al Ahmadi P.O.s in Kuwait were operated by their respective
oil companies.

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