Identification british buckle

[Lancia4]

Hi,
I was wondering if anyone would possibly be able to help me in identifying a buckle type i've found with my metaldetector.
i've found 6 of these buckles before, they're some sort of 2 piece buckle where the smaller one has a S shape, the way displayed in the photo's is the same configuration how I found them in the ground. 2 where found in a british 7.2'' gun position dump, together with 7.2'' ammo boxes in various states (one had been turned in to a stove). ration cans, rifle and pistol caliber munitions, remains of 7.2'' powder charges, and various coins from the uk and belgium mainly.
more of the same buckle where found on another 7.2'' gun position together with fuze transport packaging, damaged universal carrier parts, and firing cartridges for the 7.2'' gun.

I hope the additional information i've provided on what was found together with the buckles can help with identifying what they're from.
given the fact there was no major post war military activity where I found them, and during the war only british units where present, leaves me with the only conclusion they are most likeley of british origin, and perhaps related to specific 7.2'' HOW stuffs as munition packaging or gun equipment.

the buckles themselves are made of brass and no markings are present on them. dimensions are 39x30 mm

I hope someone might be able to identify what they're from, since i've had no succes in my search so far.

kind regards,
Lance