Looks like Camellia " White-Doves :o)

The leaves should be a lot darker which suggests to me that it needs a feed (an ericacious feed). It also looks like some Vine Weevils have been eating the leaves, so I would also spray the area to kill the grubs in the soil.

Many thanks.

Incidentally today I was clearing up the flower bed near the shrub in question and found one of those "identity tag" thingys that are attached to plants when you buy them. It was quite close to the base of the shrub in question. The tag says "Convolvulus cneorum." Could this be it? The picture on the tag looks very similar but not identical.

No! The "Identity Tag" must be for a different plant, shame I can't attach a picture to this post but here is the right up on the Tag you found.

Convolvulus cneorum, also known as silverbush, is a species of flowering plant in the family Convolvulaceae, which contains many plants described as "Bindweed".

Ok thanks. The tag probably blew in from someone else's garden!