Very rare gas mask,They were for patients who were bed ridden and unable to be moved in a gas attack. The nurses had to be in charge of pumping oxygen in for them.  I think the model is a C5 gas mask.

WW2 British home front hospital gas mask for bed ridden patients. Canvas construction mask with clear plastic face shield. 

MARKINGS:

L&B R C

DATED: AUGUST 1943