A photo showing the plants and a close up of the holes would be useful, but let's put one thing straight from the start - there is more than one variety of Photinia, but all are evergreen.

One question - were the plants supplied in containers/pots, and how long have you had them?

Thanks for replying. I have had them a month and they were in MUCH smaller containers (from a garden centre)

Sorry, I have taken a photo of one of the leaves but I don't know how to post it to this site!!!

I guess its possible they dried out a bit in their original pots, but you say you've now got them in much larger containers. Its never a good idea to pot containerised plants into something that's more than maximum 3 times the size of the original pot - too much risk of souring of the compost, and, believe it or not, its much harder to judge whether the rootball sitting in all that unused, unoccupied compost is damp or not - the surrounding soil might be, but the rootball isn't.

If, though, you've got new growth starting to appear, then likely it was a water problem, but if the leaf loss isn't extensive, it might be just natural leaf loss - evergreens do drop leaves, they just do it a few at a time. As for the 'holes' I can't advise whether that's from insect damage or an infection of some sort without seeing them. The most prevalent problem with these shrubs is Photinia leaf spot, which tends to cause brown spots on the foliage rather than holes. Sometimes a fungal infection can cause lots of holes, so that the leaves look almost lacy, but that doesn't sound like what you're describing.