Oo, a Manama cover. Those dunes covers are elusive.
Smauggie, you are clearly a person of taste and distinction.
What makes the above cover even more elusive is the date - 13/6/66. There is a story in Britain that the author Jeffrey Archer does so many book signings that the rare copies of his novels are the ones that are NOT signed! Well, in the item above we have a cover which is NOT a First Day (5/6/66) and not registered, thereby opening up the remote chance that it might be non philatelic.
The FDCs of issue 1 are like this, and not too difficult to come by:
Note that Airmail envelopes and a hand cancellor have been produced for the new Manama Post Office, but that they do not yet have a Registered cachet; the registration number is written on by hand. This is the best evidence I have that these covers were actually processed in Manama: if they had been processed in the name of Manama, but done in Ajman, they could have used the Ajman cachet - which we will see is what happened later.
By October they had their own Registered stamp:
This is sent to Stolow, a stamp agent of dubious reputation: in fact he was to become one of the two agents who went on to battle for the right to publish Manama's wallpaper issues.
By 1970 (at the very latest, and I suspect much earlier), the Manama office had closed but the Ajman office was still churning out stamps and covers in Manama's name:
Note that the Ajman registered stamp and Ajman envelopes are used but the Manama handstamp has been transferred. I am confident that throughout the 'Agency' period all and only the stamps of Manama that went through the mail used this cancel. The other covers, sold unaddressed by the Agencies were 'cancelled' with handstamps they themselves produced:
These cancels account for 99% of all the Manama cancellations you will see - all of course cto. I have done a small study of these cancels and tentatively attributed them to the two agencies, but the sound of gunshots from bored readers trying to put themselves out of their misery is becoming disturbing. So I'll finish.
At a late period in 1972, probably when the agencies were finally given the bums' rush and the post office (Ajman of course, not Manama) had to do a bit more of their own philatelic work, they created a new Manama registered stamp (copying the Ajman design, not the old Manama one) and it appears for a while, in combination with a new Manama handstamp, before Ajman finally ceased to exist as a stamp issuing entity.