Planned as part of the British Railways Modernisation Plan of 1955 to provide continuous colour light multiple aspect signalling [MAS] from London to Bristol and South Wales, Reading Panel Signal Box [PSB] opened for business on the weekend of 24th April 1965.
Originally controlling just Reading Station and the nearby junctions at Oxford Road [situated at Reading West Station], Southcote Junction, West Junction [to form the third point of the triangle] and Scours Lane, the area was gradually extended throughout the year with the Didcot area being commissioned in the May, and the former Southern Railway lines from Earley, resulting in the closure of the former SR station and the opening of a new platform 4A, on 5th September.
With the commissioning of the adjacent signal boxes at Twyford and Swindon, continuous colour light signalling was then available all the way from London to just short of Bristol.
The control of Reading Box further extended on 20th March 1972 when it took over control of the former box at Twyford, thus extending the boundary of the Panel almost as far as Maidenhead.
As part of this scheme, the remodelling of Ruscombe Junction [between Twyford and Maidenhead] in connection with the introduction of 125mph High Speed Trains, included the first use of flashing yellow aspects for a junction signal.
The final extension to the Panel along the Berks & Hants from Theale, through Newbury to just short of Westbury took place during 1977 bring the total area controlled up to approx 105 route miles.
Reading is situated 36miles from London Paddington and today the Panel Box controls 95 route miles with 246 2, 3 & 4 aspect signals, 60 shunting signals, 113 sets of points, 10 ground frames and 9 Hot Axle Box Detectors.
There are 8 level crossings in the area, 1 Automatic Half Barrier, 1 Automatic Open Crossing Locally Monitored and a further 6 major crossings supervised and operated by two crossing boxes situated at Colthrop [near Thatcham] and Kintbury, along with a further 11 user operated [accommodation] crossings…
The control panel is some 41 feet in length and was built by Henry Williams of Darlington. A second panel 13 feet 6 inches in length controls the line from Aldermaston towards Westbury.
The reduction in mileage when compared to 1977 is due to the transfer of the Didcot area to a new signalbox situated at Swindon during 1994.
The new box, designated Swindon B, was as a result of the decision to transport imported coal to the Power Station at Didcot from Avonmouth Docks near Bristol instead of the more tradition coalfields in the Midlands.
An extensive track remodelling of the Didcot area was required to handle the new traffic flows and it was decided to provide a completely new signalling installation for the area, and the new IECC [integrated electronic control centre] was provided as a precursor to the Swindon Mega-Box idea of the early 90’s which would have seen the closure of all the Panel boxes between London and Plymouth.