Plus parts of the South Hams and West Devon

  Brian Moseley, Plymouth
Webpage created: April 29, 2018
Webpage updated: April 15, 2021




The second, timber-built Plymouth Mill Bay Signal Box.
From the author's collection.

The approach to Plymouth Station (Millbay) from Cornwall Junction Signal Box, at 246 miles 26 chains from London Paddington via Bristol Temple Meads, opened in 1878 and replaced from July 2nd 1899 by a new 30 feet 5 inches by 12 feet, 39 lever Box that survived until November 26th 1960, when the Plymouth Panel Box was opened.

The original Box appears to have been between the lines from North Road West and Devonport Junction.  The new Box was at the actual point of the Junction, on the UP side, backing on to Archer Terrace.  There were two Up Sidings behind the Box, attached to the Cornish Down line.

The main lines then passed, on the right, one of the buildings of the Plymouth Engine Shed. In 1892 this contained four roads, one of which ran through the building and out behind it.  There was also a siding between the Up main line and the Shed.  Hidden behind that Shed was an even bigger building with six roads, at the rear of which was a turntable, which as it had only one other line linked to it was simply for turning locomotives.  The second Shed was adjacent to Belmont Street,  the houses facing the building.  To the left of the main line, on the Down side, were three long sidings adjacent to Harwell Street, which joined the main line by a trailing point just before the main lines crossed King Street Arch.  On the bridge, on the Up side, was the access to the Shed and a building on the bridge looks like it may have been the King Street Ground Frame.

By 1912 the scene had changed somewhat.  The two engine sheds and the turntable were still there and the three Down sidings   had grown to 4 and been enclosed to house carriages, but there was now a facing junction beside the four road building, which formed the Plymouth Great Western Docks Junction.  The building on the King Street Arch had disappeared but a new Signal Box had appeared on the inside of a boundary wall that now separated the sheds from the main line.  This was presumably Harwell Street Signal Box.

Six tracks now crossed a widened Arch over King Street, Down and Up main, Down and Up Docks and two others.

Just after passing Summerland Street on the Down side was a building high up on an embankment.  By 1912 this was still present but had been joined slightly to the north by a long Signal Box, in front of which were now eight tracks.  Nearest the Box were the Down and Up Main Line, which led to Platforms 1 and 2 and from Platforms 3 and 4 of Plymouth Station.  Next over were the Down and Up Goods lines to the Plymouth Great Western Docks, which also connected with the Goods Depot.  This line was subject to a 5 mph speed limit.  Finally, on the far side, were four sidings linked to the King Street Ground Frame.

Plymouth Mill Bay Signal Box is said to have had two incarnations.  The original Box was built of brick and was inspected by the Board of Trade in July 1899.  It allegedly measured 70 feet long by 14 feet wide and contained an 117-lever frame.  It may not have been brought in to use until the rebuilding of Plymouth Station was completed in August 1903.  This Box was situated at 246 miles 48 chains mile post mileage.  The second incarnation was built of timber, was located at 246 miles 50 chains, slightly to the south of the original Box, and was brought in to use in June 1914.  In the photograph below of this second Box it looks like the building to its left might have been the base of the original Signal Box.   


The rear of Plymouth Mill Bay Signal Box.
Mr Patrick Lynch, Bristol.

This Box held 115 levers and measured 58 feet by 12 feet.  The Distant Signals were now fixed at danger.  Although the layout was the same as before, the points were disconnected for nine days and it took 22 groundsmen to signal trains and shunting movements during that period.  The platform lines were provided with track circuits in 1922, until which a special locking system was used that prevented the signalmen from allowing trains into platforms that were already occupied.  There was an impressive gantry of six Down Home signals at the entrance to the Station.

The "Is Line Clear?" for departing trains was to be sent when the Platform Indicator indicated that the train was ready to leave.  During fog or falling snow the Platform Starting Signals must not be lowered until the "Line Clear" code has been received from Cornwall Junction Signal Box.  For trains arriving at Plymouth Station the "Line Clear" code could be returned to Cornwall Junction Signal Box only if the track was clear to the buffer stops and the points had been set for whichever platform was required.

Lever 30 was locked with lever 6 at Mill Bay Level Crossing Signal Box released the Dock Line Ground Frame.  This Ground Frame only worked the points for accessing the Fish Dock and two Catch Points within.

Between Plymouth Mill Bay Signal Box and Plymouth Station was for many years a Ticket Platform at which the tickets of arriving passengers were collected before the trains entered the Station Platform.

Plymouth Mill Bay Signal Box was closed on or as from December 14th 1969.


  With grateful acknowledgement to the late Mr Laurence 'Larry' William Crosier (1929-2010) of the Great Western Railway Company (1943-1947);
British Railways (1948-c1994); the Plymouth Railway Circle, the Lee Moor Tramway Preservation Society, and the Signalling Record Society.