View source for SN.20

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[[File:SN20.jpg|thumb|400px|right|SN20 (left) and SN620 (right) Signals ''(Photo by Danny Scroggins)'']]

==Origin==

This signal previously [[DM.72]], but was converted into a controlled signal when [[Bourton]] Interlocking was commissioned on 1/10/77, as described in the following WON entry:

[[File:1977-08.png]]

The signal was formerly an automatic - [[DM.72]]

==Conversion to four-aspect==

The signal was converted from a three-aspect head to a four-aspect head, and positioned on a new gantry at 04.50 on Monday 14 January 2002. The top yellow was not yet brought into use.

[[File:WON-2002-01.png | border]]

The top yellow aspect was planned to be brought into use on 7 February 2000, as described in [[GWS.15]], but, due to 'construction difficulties' the work did not take place.

[[File:WON-2000-03.png | border]]

The top yellow was then planned to be brought into use on 11 February 2002, as described in [[GWS.27]].

[[File:WON-2002-06.png | border]]

and

[[File:WON-2002-03.png | border]]

but wasn't until 18 February 2002....

[[File:WON-2002-04.png | border]]