Fork relay incorporating magnets type D-251-A, no. 297473, by Muirhead and Co. Ltd., July 1957 Fork relay incorporating magnets type D-251-A 1957
Fork relay type D-14 no. 87, by Elliott Brothers (London) Ltd., 1944, used on Cable and Wireless Co. Porthcurno-Maderia submarine telegraph cable until end 1969 Fork relay type D-14 no. 87 1944