I've gone half-SteveCH:
https://www.sportsbikeshop.co.uk/motorcycle_parts/content_prod/203789
It's got a hood that is folded into the collar. Not sure if I really want that - time will tell whether it's a boon or a pain.
It's a pain. I cut the hood off. Really not needed, and makes head rotations slightly awkward. It might OK on a sit-up-and-beg bike, but not a K1300S.
They didn't have the matching trousers in my size, but I did have a gander at the BMW Rain Lock ones at Wollastons, and they looked better, with non-slide patches on the bum:
https://www.bmw-motorrad.co.uk/en/wear/ride/rainlock-wet-weather-suit.html
I went for the BMW Rain Lock trousers mentioned above.
XXXL fits a fat Richtea nicely. North Oxford BMW got two extra sizes in just for me, so I was quite impressed. Most shops just shrug and say 'Haven't got that size in stock.' Well done, NOG.
They're also on sale at the moment if anyone else needs a pair - £50 instead of £69, which helps, but ring first just in case not all dealers are doing a sale (I know that Wollastons were too, though).
They're even lighter material than the Held jacket, but the NOG guy says they're still quite strong, but I guess I'll need to be careful not to catch them on the pegs too often. They have v long zips up the inside legs for ease of climbing in.