Sight identification

[rnixartillery]

After a successful few days away parts hunting I picked up this unusual 25 pdr (I think ) Sight unit. I have not seen one of these before so if someone out there can clarify what it is that would be great.
I have attached several photos but it is clearly for the 25 pdr and has a very Italian look to it so I am guessing it was supplied for the post war Italian 25 pdr's, but it is measured in yards ? the box also has characteristics taken from the British post war metal dial sight case.

It is stencilled No 31 dial sight carrier and made by Grundy Tedo Ltd

Can anyone shed any light on this please

Rob..................rnixartillery.