Air Ministry? and Bratt Colbran marked rope pulley any information on its use?

Please excuse my ignorance as I am new to this subject but I recently came across a rope pulley marked Bratt Colbran 1940 and understand they were suppliers to De Havilland. Can anyone shed any light on this item with regards to its use or was it just general? “AM” and the crown are also stamped so I am presuming that this was an Air Ministry item?[ATTACH=CONFIG]245254[/ATTACH][ATTACH=CONFIG]245255[/ATTACH][ATTACH=CONFIG]245256[/ATTACH][ATTACH=CONFIG]245257[/ATTACH]