Telephone operators provided essential support during WW2, whether at GPO (as they were before BT) exchanges or at Police, Fire Brigade, ambulance and Civil Defence units, in the event of a gas attack they would need to carry on connecting the various services so that they could be directed to bombed and gas affected areas.
This mask is a typical Civil Defence respirator with a scarce microphone and headset fitted. The filter is dated 1937, the strap pad is 1938, mask has a 1946 stamp which was presumably when it had a service or a change of filter perhaps. Complete set with headset, microphone and jack plug. There is perishing to the rubber around the edges but it it still supple. Comes with large bag which was also used with the mask for those with severe breathing difficulties or serious facial deformity, the bag is a bit tired but still good, there is a small tear to the rear.
WARNING: Respirators should NEVER be worn.