Fascinating information Mike!
I’m very glad that one with an interest in firearms history, and the willingness to report, has this rifle.
Of course, there is also the opportunity for me to have a good look at it in person some day!

My supposition is that many higher rank British officers did often order sporting rifles in the same chambering as the adopted military round as supply of appropriate ammunition would be always at hand wherever they may be in the Empire.
Therefore, I’d not assume that a rifle such as this would be left at home in the UK during deployment but, rather, would have been taken abroad with the officer.
Glad you have it!