Mike
seriously, the run really is that long. I've had long discussions about it with BT engineers over the years.
Locally BT did a lot of very strange very experimental things and we're still suffering from them here
Other examples were the first fibreoptic trunking in the UK, and a hybrid prototype exchange which used strowger switches to set up digital lines. Weird
BT had an engineering lab locally - though local rumour had it that much of the work done there was into stuff now done at places such as Cheltenham. Guess thats another "fact" that'll never be confirmed