An ingenious method of hiding a compass inside a collar stud that would have been issued to some aircrew and worn with their RAF shirt/collar. Made using a cheap gilt metal collar stud with integral compass pivot and rotor. The glass top would have originally been painted white to hide the compass beneath but this has been scraped off. Interesting to note that many of the studs used for this purpose were actually purchased from Woolworth. When 'downed' in enemy territory this could help the unfortunate airman back to safety.
Unfortunately this example seems to have moisture under the glass and this prevents the rotor from functioning. Still a rare item. Priced accordingly. Stock code E19975.