WW2 Naval Cover Help Please

I have just got this cover and wonder if anyone can throw some light of the various postal markings and possible the unit addresses / abbreviations. All I know at the moment is A.P.O. CS1 was the Canadian Postal Corps HQ in Acton, London

It is adressed to a
D-10140 Pte. Rankin L.B.
C.M.H.2 D.2.S.
Canadian Army Overseas

With these postal markings
Two line blue FROM H.M.C. SHIP / EXAMINED BY DB/N 557 hand stamp.
Red POST OFFICE / MARITIME MAIL undated double circle
Machine cancellation ARMY POST OFFICE / SC 1 / 5th April 1943
Pencil manuscript att'd #43 coy.Cu AC

Thanks in advance
AQ

I have the book titled "The Royal Canadian Naval Postal History 1939 - 1945" by Maurice F. Hampson. Unfortunately, although there is a list of the DBN markings, he goes up to DBN #556 and skips to #560 with no information at all on your DBN 557. This is unknown at present. Also, I cannot find much information on the "Maritime Mail" markings presently. Will see if I can dig anything up. Your "ARMY POST OFFICE SC 1 is called a double impression Kragg machine cancellation. Sorry I can't offer more.

Chimo

Bujutsu

Bujutsu

I appreciate your help so far. What do you think of that book I see that there are 4 volumes published around 1994. Is it worth keping an eye out for ?

AQ

Hi AQ

I would say that the reference books are worth their weight in gold. I have stated this for any specialized reference material. The only downside to reference books is that once it was published, some historian/ researcher will find something that outdates the information. But, that is not a bad thing because the topic is still active, alive and well. To sum up, I would say, 'yes', keep an eye out for any of this kind of material like the one I pointed out.

Chimo

Bujutsu