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.