Omega 2165 Question: Military (British) Provenance?

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I own a fairly nice 2165 and came across this example. While the watch is, otherwise, exactly like my own, information in the case back includes several things not found on my watch case back:

s-l1600.jpg

Those things include:
1. The "A"
2. CS (I)
3. The second number, 1119

Do any of these markings indicate any particular connection between this watch and the British Military?

The below is a shot of the case back from my watch:

s-l1600.jpg

Thank you for your indulgence

Wayne