"Nigel Pendse" wrote in message
. ..
Are they 1972 cars moved to supplement the 1967 stock?

Partly, yes. The unit concerned is 3086-4086-4186-3186, which was part of
the last train to be refurbished (along with 3016 unit). It was
experimentally fitted with the altered seating-layout, and also you might
notice that the inner ends of the cars are painted grey as an experiment
into hiding the dirt that builds up in these areas. 3016 also has this
feature.

Coincidentally, cars 3086 and 4086 are converted 1972MkI cars, however this
happened way back in the 1980s, and has no connection whatsoever to do with
internal differences.


HTH.