Sorry to take so long in replying, folks, and many thanks for your suggestions. I've got Osmanthus B and Olearia and I used to have choisya and it's not any of those, though I'd say the nearest suggestion is Osmanthus decorus. Only trouble is, the tiny white flowers on this were single, not in any kind of cluster, and completely devoid of scent.
Oh well, it's proved its worth as an elegant shrub that really thrives in dry soil, so although I'm planning to cut it down to make way for something else, I've taken some decent cuttings.