This might help put a value on it
https://www.davidlay.co.uk/auction/lot/92-t-gwyn-elger-fras-the-moon-a-full/?lot=47780&sd=1
British Astronomical Association
Supporting amateur astronomers since 1890
Supporting amateur astronomers since 1890
This might help put a value on it
https://www.davidlay.co.uk/auction/lot/92-t-gwyn-elger-fras-the-moon-a-full/?lot=47780&sd=1