I think it might be Euryops, maybe E chrysanthemoides or E. pectinatus - under magnification, the picture you've supplied is too fuzzy to tell. It's a half hardy shrub, so the first hard winter we get, or even a proper winter, its likely to be killed back or die, unless you live in a warm, built up area (like London). Average height and spread over time around a metre, usually wider than it is tall.

Hi, welcome to GoY, I agree with Bamboo, but can you tell us the height of this plant, it doesn't appear to be very tall to me, and if it's only about 12" high' it could possibly be E acraeus, which is borderline fully hardy, Derek.

Borderline indeed, Derekm - I lost mine in that winter of 2010 despite its sheltered, sunny position and being covered, but you're right, it might well be E. acraeus.