Agner Krarup Erlang, Danish mathematician, c 1915.

Telephone kiosk protected by sandbags, 26 September 1939.

Post Office 706 telephone, c 1959.

'New Sorting-room at the General Post Office', London, 1846.

'School telephone' in polished wood case, 1921-1940.

'School telephone' in polished wood case, 1921-1940.

'School telephone' in polished wood case, 1921-1940.

London Chief Post Office

'Sketches at the General Post Office', London, 1875.

Gower-Bell telephone, 1881.

Gower-Bell telephone, 1881.

Crosley table telephone, 1879.