On Sep 22, 5:40 pm, "Clive." wrote:

As I remember my time on the Northern Line, trains were composed of four
and three car sets, each three car set being composed of only one
driving car and a panel driven (30000unit?) Now as all the driving
cars were either "A" or "D" end and as the units were uniform it would
suggest that all the 30000 units were either "A" or "D", I suspect "A".
At that time, only "A" and "D" units could couple under normal
circumstances. This is why I suspect press reports about six car
trains. As I've said I suspect the trains were only four cars long and
this came from seeing them in 16 foot tunnels and eight car platforms,
but if you can provide me with more accurate information, I'll happily
apologise and back down.
--
Clive.

From 1970 the Northern City fleet was maintaind by Neasden and had a
segregated fleet of 3 car 1938 stock units (they had to be segregated
as they had Northern Line maps). These ran as six car trains on the
branch.

The cars involved in the Moorgate collision were DM 11175, Trailer
012263, DM 10175, DM 11115, T 012167 and DM 10115.