There's an excellent film called "The First of the 13" about the
Dartford resignalling (made by someone who worked on it) on the
'Terminus' DVD:

http://www.amazon.co.uk/Terminus/dp/B00081MX60

Didn't mention what the other 12 were to be..but here's a guess:

Waterloo
London Bridge
Victoria
Feltham
Woking
Ashford
Three Bridges
Portsmouth
Eastleigh

+ 3 others.