A portable anaesthesia machine manufactured by British Oxygen Company (BOC).
BOC bought King's (anaseathia machine salesman) company in 1939 and Coxeter's (medical instrument maker) in early 1900's. It was likely used in field medical tents and hospitals during WWII but became more readily available mid century.
There is a large amount of associated items that compliment this item.
.%20BOC%20bought%20King's%20(anaseathia%20machine...){kind=link}