Several Post Office pattern sounders.

Back row, from left to right:

Sounder with milled terminals marked underneath “Maison Breguet”.

Unmarked Vyle´s pattern polarized sounder.

Silvertown, London E.

Front row, left to right:

A.E. Co. Ltd. A.T.M. Liverpool.

Vyle´s pattern polarized sounder  marked “Walters Elec. Mfg. Co. Ltd. Makers London”.

B.I. & C. Ltd. Liverpool.