Can anyone help with discovering the headlight codes used on the Northern? My Ian Allen ABC dated around 1959 says all 5 lights were showing for all routes on the Northern, whilst all other lines had a comprehensive series of codes for all destinations. After that date the provision of code lights on DMs was dropped on new stock. But what was the case with Standard Tube Stock?
This doesn't say how the codes worked on the Northern for Standard stock although there were fewer destinations then (I think only eleven possibilities rather than the 21 available when the Northern Heights opened), so four lights were presumably enough.
The 1956 stock were the last new DMs to have headcode lights.