You can prune them back now and you can be pretty rigorous if you want to be, it'll encourage new red leaves eventually. You need a pair of sharp secateurs, trim stems back to just above leaves.

Thanks Bamboo, Sorry if this is a silly question.
Should I prun e new shoots back, or more established branches with no red leaves, or just go for it and prune everything. I would like to have a healthy bushy plant rather than the long straggly branches I have at the minute.

Thanks for asking Willgrow - I'd been eyeing up my new-ish Photinia and wondering the same things.

My feeling about these situations is always the same - if the plant looks straggly, thin and unattractive, it's going to get a good hard cut back, to which hopefully it'll respond - and if it doesn't, then I'll replace it, rather than put up with something really rather unattractive because I'm afraid of killing it, particularly with a plant so readily available and not that expensive such as Photinia. That said, I would only do that hard cutback at the right time (not, for instance, in late autumn) which would be now for this plant, because that gives it the best chance of a full and beautiful recovery from the surgery. Photinias are often used as hedging these days, and get cut quite often when used as such. I did hack back a tatty Photinia which had been in a large pot for too long and looked awful, and planted it out - 1 year later, it looks fantastic, as most likely will yours, and by the end of this summer, if not before.

Thanks again Bamboo, I trawled the internet for hours trying to get some clear for information and guidance on this with no success. You're a star!

Pruned, Boss! :-)

Hmm, I have this image of you standing bolt upright, heels together and saluting, Beattie, lol! Can I just say that, although I give out information in what must seem to be a very definite manner (lol!) whether or not you follow what I recommend remains the reader's choice;-))) It is true I have the tact of a house brick...

lol So have I! :-) (that's the image and the tact...)