The Westinghouse Brake & Saxby Signal Co. Ltd produced the Style 'V' mechanically locked lever frame from 1954, and a total of 91 units were manufactured. The first instalation was at Aldersgate controlled from Farringdon cabin. this was commision on the 8th December 1954.
It was Rober Dell and Walter Owen from London Transport and the British Transport Commision who patented the 'V' style interlocking miniature lever frame.a provisonal specifiction was created on the 26.4.1954 followed by the complete Patent 770187 on the 23.5.1955 and was granted on the 20.3.1957
Full details of the patent are available in the following 5 PDF files