Northern Line 

A selection of diagrams showing the signalling arrangements for sections of the Northern Line at different times throughout its history.

	Northern Line Extensions 1939-1941 A set of diagrams showing the details of signalling on the Northern Line between Archway and High Barnet when LPTB services were extended over the former Northern Heights Line in 1939.
	Northern City Line A set of diagrams showing the signalling in the controlled areas of the Northern City Line at Finsbury Park, Drayton Park and Moorgate. As my information on this line is rather scant, the diagrams represent a 'best guess' and are therefore not guaranteed to be completely accurate.

Most of the diagrams are in PDF format and to open them you will need Adobe Acrobat Reader. If you do not already have this it can be downloaded from the Adobe Website.