I think your's was made by Milbro in England (Scotland?). This company got the rights to make Diana's following WWII. I would guess your's is from the late 40's or thereabouts. Don't have a picture, but the Model 16 is listed as also sold here, rebadged as HyScore 805 and the Winchester 416. Hey, here's a HySCore 805 on Gunbroker:
http://www.gunbroker.com/Auction/ViewItem.asp?Item=98643115
Look like your's?
Value depends upon condition. I don't think it will be high, but there are collectors who may pay a premium for a nice one and you don't see many 16's. The Milbro guns seem to bring less as they were a bit less well-finished, but there seems to be more interest in them lately. And, again, someone may need to fill that void in their collection.
How about a picture?