Fascinating. And I’d say pretty much spot-on accuracy, as to what an FTTP network would look like, albeit modelled on coax which was the available technology.
Re Post Office Dollis Hill, my own understanding is they provided one or two vaguely useful contributions, such as the world’s first programmable computer, the Colossus used at Bletchley Park.
Arguably, I’d suggest their closest US contemporary might have been Bell Labs, which contributed things like the transistor, the laser, Unix, ‘C’, among many other pretty amazing inventions and creations.
Not convinced about Darpa’s overall creative influence, wasn’t their mission strictly military, albeit with beneificial side-effects?
As for date, there was a reference to a charge of one new penny, so I’m guessing very early seventies. One interesting point, the lady dialling the number on the console dialled in an 07845 number. That would be a mobile number today, maybe they forgot to mention the plans for mobile networks?