Hi Guys, most British WW2 aircraft carried these. As the name suggests, they were designed to be used by crew members to free themselves from crashed aircraft or to be used as a general survival tool. The handle is insulated with thick rubber and so it could be used to cut through electrical wires.
It is dated 1939 and maker marked "Elwell". The other mark is the Air Ministry stamp of the Crown and "AM".
British Airborne troops sometimes used these after taking them from their Horsa gliders. They made a vicious close combat item. One was just recovered this year in Arnhem on the positions of the King's Own Scottish Borders.
I picked this one up on a vintage tool stall at a vehicle rally some years ago for a tenner.