Danish gas mask M/45 E - British Light Anti Gas Respirator, Mk 1 - WWII
The "Light, Anti Gas Respirator, Mk 1" was designed to free the masked soldier from the cumbersome breathing hose and large box filter commonly used with most early WWII gas masks. (For instance the Service Respirator, Mk. V or the Service Respirator, Mk. IV )
The rubber face piece was derived from the civilian type respirators (the Civilian Duty Respirator in use with the civil defence units)
The mask was fitted with large inhale (60 mm) and exhale valves to reduce breathing resistance.
In Danish service, the mask was designated the M/45 E. M/45 - because it was introduced in 1945, and "E" because it was "Engelsk" = English.
My particular gas mask continued to be used by Danish Civil Defence Organisation - Civilforsvaret. Hence the white CF stamp, and the date (19)54.