In 1923, the Great Western Railway replaced the North (NGR: SH 58221 00712) and South (NGR: SH 58397 00563) signal boxes at Tywyn station with one larger box removed from Maidenhead East. This box had most probably been first erected, along with Maidenhead West and Middle, when the track between Reading and Maidenhead was quadrupled between 1890 and 1893. By 1923, Maidenhead East signal box was being affected by subsidence; a new East signal box was built opposite the old box which was then dismantled and moved for re-use at Tywyn.
Towyn Signal Box is a GWR type 25 design, dating from circa 1893 (when the 'rocket' roof vents were introduced). It is a four bay, all-timber, horizontal weatherboarded two-storey structure, under a pitched slate roof with a wooden access stairway and a porch, similarly roofed, at the south end. The frame has 39 levers and is a Great Western Railway 3-bar Vertical Tappet or 3-bar Horizontal Tappet type.
The box was demolished following the introduction of Radio Electronic Token Block (RETB) signalling on the Cambrian Line on 24 October 1988.
Sources include: C.C.Green, The Coast Lines of the Cambrian railways, Vol 2, Wild Swan, 1996; The Great Western Archive (www.greatwestern.org.uk), 2017; The Signalling Study Group, The Signal Box - A Pictorial History and Guide to Designs, OPC, 1986; Aerofilms photo EPW022623 of 1928).

B.A.Malaws, RCAHMW, 21 October 1988 and 03 February 2017.