Clementii

These can be propagated by taking cuttings, Libby, so you can have more than one after this year :-)

Oooh I'll be planting them everywhere lol.

Many plants from warmer climes live less in northern climes and are treated as annuals almost. But plants are generally highly resilient and if they are in a warm microclimate it can make a tremendous difference. After a while you may find this mallow is self propagating as it seeds itself, but first off I would follow Xela's advice.
Gardening tip. Best to do the 'looking up' before you buy. Try leaving an old garden book in the boot when you spot something.

Good idea with the book Muddywellies, I may do that, because sometimes the person at the shop doesn't have any idea.

Lovely colour. Maybe too cold for it in the N.E. of Scotland.