I don't recall seeing so many leaves discoloured red/purple as there is this year on this bush. This one is full of them, whereas the other two don't have many.
Is this a problem?
The plant has been stressed by something ... it could be the dry winter and spring, but I think it's more likely to have been the very cold Arctic air that passed over the country a couple of weeks back ... it seems unbelievable now that it was so recent ... but we've seen a lot of photos of cold-damaged new hydrangea leaves since then.
Could well be. It is the bush that gets the wind firs, so it does get ruffed up more.
Should one do anything to help it?
New leaves will appear Stephen so you don't really need to do anything. Those ones will drop off. You could prune off (very carefully) the damaged leaves as they die back, but I would leave them unless they become very unsightly.
Okies, thanks everyone I was concerned it might have been a fungi or some disease but if it's just weathering I'm reassured