The switch to 7 car was also to avoid use of narrow 'catwalks' at the
ends of some central area District Line platforms which were in danger
of falling foul of the Railway Inspectorate (today's Heath & Safety
fascists), and even using these narrow channels (still in place at
certain stations) required the 'end door cut outs' to be operated to
stop the first and last sets of double doors opening on an 8-car train.
What chance of this in today's nanny state?