Last week saw a woman riding a Segway through town, it had disabled stickers all over it

I thought there was some legal stuff which made them illegal in the U.K.

There is unless its registerd as a disability vehicle. If you register a vehicle as a disability vehicle then you can sidestep construction and use regs.

I saw a very chic couple , 2 up on 1 going down the path in Mayfair.
On the front was a disabled badge that I can only assume their grandchildren had made for them.

They’re not – but no-one seems to care much.

The disability vehicle thing means limited to 4mph on pavements, 8mph on roads, and I don’t think Segways do that.

segways are faster than that. pretty sure they are illegal and can’t be reclassified like that.