Does anyone recognisize this gun site?

[Ron Pier]

This site is up for sale by a friend of mine. It's made by Cook Troughten & Sims.

[Geoff Winnington-Ball (RIP)]

I don't know what kind of reticle it has, nor what other range markings it may have, but it's size and configuration suggests perhaps a mortar sight.

[Bob McNeill]

looks like a director to me

[Ron Pier]

Sorry about the spelling blooper! Of course it's Sight, as in seeing not Site as in building. (Stupid boy)
For comparison here are the sights/directors on my 3" mortar and Vickers MG.

Ron

[Wayne Henderson]

My money's on Bob, a director. Check for a date, mk and no. markings that should be there under the paint just above the Left/Right degrees guide on the base.