Strong cold winds can do this.

Based on your garden centres comment I have to ask is there any industrial chimneys in the area?

If so they might be throwing out toxins that are affecting plant life.

Then there is the possibility of acid rain which can originate from further afield.

Or have you been doing any spraying recently?

For example; the house wall behind?

What I can't understand is; the top growth seems OK and what ever caused this happened some time ago before the top growth formed.

To be quite honest I don't really know but it certainly looks like overspray of some substance that is toxic to plants!

Teegee, I thought that myself. It's certainly not anything that has been used on the house wall. However, I did use a new insecticide/fungicide at the start of the season - as I have always done in the past with my other roses - but they were also treated with the new spray and none of the other five has suffered. I suppose it could be that this rose was too young and the new spray possibly too strong for it. But, this doesn't really explain the same problem on the other stuff which hasn't been sprayed. Now, we have had some awful weather, and if I remember correctly, it became incredibly cold a couple of days after I sprayed. That is the only conclusion I have come to if it's not Rose mosaic virus.
The question is, should I do anything with the 'manky' leaves or the leave the plant to get on with it this season? I notice that it's got a couple of buds so I don't think it's actually dying. It just doesn't look very pretty!

It is a mystery to me as well!

Personally I would remove and destroy any affected leaves as I don't think they are of much use to the plant now.

A thought has just struck me!

What type of organic matter did you dig in?where did you get it,and did you dig it in elsewhere e.g.where the other affected plants are?

I am wondering if your organic matter is contaminated in some way?

I ask this because in the past I have been affected with contaminated manure, OK the symptoms were a bit different but I thought it could be a possibility!

I think you will be aware that I am clutching at straws but mysterys like this intrigue me!

I look forward to your reply.

I dug in loads of compost that I buy from the local GC. Not commercially bagged stuff. But it's the same compost I put on the garden as a mulch in spring which I then dig in during the autumn. So, it's the same mixture I've put on the whole of my garden! It's certainly a bit of a mystery eh? I suspect that it could well be a combination of the spray I used followed by unusually very cold weather. I'll keep monitoring it to see how it goes and keep you up-dated!
Thanks for your interest.

Is this Rose Mosaic? Caused by Prunus necrotic ringspot virus and apple mosaic virus pathogens.
The leaf symptom is a pattern of light and dark green areas that give a mosaic effect in infected leaves. In roses, only occasional effects on flower production has been reported but foliar symptoms detract from the overall quality. Infected plants tend to be less vigorous than healthy plants and are more sensitive to winter injury. The degree of symptom expression varies with the cultivar, the time of year, and from year to year. In general, symptoms are more evident in the spring. The entire plant is always infected; however, mosaic symptoms may not show up until the weather turns cool, a condition which favors virus disease development.

Thanks Drc. As I mentioned in the question, I had also wondered whether it might be mosaic virus. But, I'm not convinced as too many other plants have similar symptoms. Like TeeGee, I'm now thinking that it could be something in the compost, or as the local GC said, it could be just down to climatic conditions. I'm going to monitor evrything and see how they go.