Aberthaw Signal Box stands on the on the platform of the demolished Aberthaw High Level Station (nprn 41424) about 100m to the west of Station Terrace in East Aberthaw. The signal box was opened in 1897 as a part of the Vale of Glamorgan Railway from Barry to Bridgend, incorporated into the Great Western Railway at the 1923 Grouping.

The structure is a Barry Railway Type 2 signal box, a type individual to the Vale of Glamorgan Railway, and now one of only two of its kind surviving and in use (the other example is the Operators Cabin of 1889 at the Sliding Bridge, Barry Docks). The box still controls the junctions and sidings for Aberthaw Cement Works (nprn 40673) and Aberthaw Power Station (nprn 269878), although not all the levers are in current use. The brick-built ground floor locking room has three arched windows with glazing bars while the timber-framed operating floor above is glazed in four bays with small panes over larger ones. There is a door to the locking room and timber stairs to a gabled first-floor porch on the southern gable. The pitched roof is slated and has plain bargeboards and spike finials.

The interior contains an NX panel and Great Western Railway lever frame of fifty-three levers, with vertical-tappet interlocking, which was installed in 1962 and is a unique design for the Vale of Glamorgan Railway. (correction from P. Kay indicates that the box contains an IFS (Individual Function Switch) panel).

Sources include:
Field observation, B.A.Malaws, RCAHMW, 02 July 2014;
Cadw listed buildings description;
The Signalling Study Group, The Signal Box - A Pictorial History and Guide to Designs, OPC, 1986, p 169;
Peter Kay, Signalling Atlas and Signal Box Directory (Third Edition), Signalling Record Society, Wallasey, 2010;
Network Rail, Signal Box Register (undated);
A Guide to the Industrial Archaeology of South East Wales, AIA, 2003.

Claire Parry, RCAHMW, 20 June 2011 & B.A.Malaws, RCAHMW, 04 February 2015, 02 September 2016.