No idea on the neighbours, Seph, I'll have to check when I get home. I can VPN in though, so the connection can't be that bad (And the ping graph has calmed down a bit, it seems)- I just can't reboot the hub (unless someone can point me to a way of doing this remotely?).
Just for completeness, here's the stats:
As you can see, everything except that particular upstream seems to check out.
I'm hoping that another reboot will get it back on, but if not then hopefully even on a single upstream I should still have a usable connection. The wife has a raid tonight, so that'll be a good test!