Thankyou John and Peter. I feel we have made some advance with the Air Ministry - I was convinced it was Naval, which is why I put it on this sub-forum. A friend - who I think belongs to Forum, but doesn't post - has pointed out that the bars on the compass show military use - he thinks 1930's for them - and cleverly, has pointed out that they have been stripped of their original paint, to show the brass which is more attractive in a collection. If they are from the RAF - then how and why, did they use them. I can't imagine it being on a plane - was it at the aerodrome - to guide planes in ? Another thought - could it be anything to do with anti-aircraft guns - or, observers posts?