Well finally got the install done and as to the sliver GPO box, the engineer had no idea!?!?
I guess he was too young to remember antiques .....
As for the Cab across the street, it seems, yes it is a new 'terminating' FTTC cab, but my phone line from this cab, goes back up the street and around the corner to another cab and back to my house.
It's from this further away cab I get my line, so I'll lose some speed ....... you really couldn't make this stuff up !!
I'll leave the install to settle and report some speed tests in due course. Just have to think about which router to replace the Home Hub with.
By the way, the kit supplied a HH3 and I've emailed to complain and ask why the new install didn't come with a HH4 !!