Jim S wrote:

Thanks Dave.
Spot on.
It's weird - no sign of chlorophyll or real flowers.

Ah, but if you very, very carefully peeled away the silver indumentum
on the stems or tore back one of the scale-like leaves, you'd see the
chlorophyll. There's plenty there - it's just covered to protect the
soft tissues from burning in the intense light of its natural habitat
as well as preventing excess transpiration in dry, windy conditions.
The real flowers are those button-like heads. They form hard,
spherical masses composed of many hundreds of tightly packed florets.
It is related to the Asters and Chrysanths and is only lacking the
outer ring of ray florets to show its alliance with the rest of the
daisy family.

Jim, I've noticed you're up in Tyne & Wear. Best bring it under cover
for the winter in your part of the world. A frost free or gently
heated, brightly lit position will suit it well. Just keep it
sufficiently moist to prevent total drying out. It is well worth over-
wintering since 2nd. year plants make very handsome mounds of silvery
stems.