Rose powdery mildew by the sound of it - spray with something like Roseclear ultra, but preferably at dusk when the bees aren't working. Or try the milk solution - one part milk to nine parts water mixed in a sprayer, spray with that, covering all stems and leaves.

Thanks so much really appreciate your help.
I will try the milk solution tomorrow and will look for the Roseclear ultra if the milk solution is not successfull.
Regards Marybo

it's almost certainly as described, and there's no clearing it with any spray, unfortunately. A hard cut back to good clean growth, then a preventative spray might stop the mildew on the new growth.

Yes definitely agree with last comment. You have too cut right back. Then when new growth appears. Spray with a suitable pesticide.

pesticides don't work on mildew. needs to be a fungicide.
also lift any drpped leaves as that will harbour and fungal spores.
is the rose against a wall? if it is in the winter/early spring re arrange the trellis so it stands 4" clear of the wall. the growth will benefit from a clear airflow around the back of it, reducing the humid conditions that the fungus prefers.

Mine had this last year but fortunately it has been a different story this year, some of the other roses in the garden are doing it, think all the damp conditions, rain and then sun and high humidity have caused a lot of the damping off of the roses. Shame but they do get better, maybe next year. I love Tess of the Durbervilles it is a beautiful rose last year the rose didn't have much perfume either, this year it is amazing. Good luck with it.

Thanks everybody for your input ~ I now feel happy that I can tackle theproblem without loosing the lovely Rose.