RISC OS S.V.R. S&T Department RISC OS
http://www.svrsig.org/ diags/S176.htm

Morris Cowley

The dog chart and associated locking table, derived from the dog chart, show the position as at 15 February 1954. The relevant dog chart was marked up to show provision of lever 9 to control a ground frame in advance of 40 signal (into use 30 January 1955).

A subsequent dog chart and associated locking table, at amendment A (May 1961) shows that track circuit locking has been installed on FPLs 29 and 33, with lever 27 becoming spare and lever 29 becoming the FPL for both 26 and 28,each way locking on 29 and 33 being removed.

A box diagram may be consulted in the publication 'Princes Risborough-Thame-Oxford Railway' by OPC, although this is for a later date. The changes are that levers 1 and 43 are shown as spare (these were working distants), lever 3 is shown as spare but was an up home signal located where the bracket (4/11/12) is now shown and the bracket was at 15B points. When track circuits were installed, FPL 16 bolting points 17 became 14A and FPL 27 bolting points 26 points became 29A.