Still difficult to see individual leaves where the problem is, sorry.

Have you fed it this year at all? If not, buy some specialist rose feed while you're at the garden centre, something like Toprose, as well as spraying with Roseclear.

Yes, I do have some rose feed and no I haven't fed it so I'll do so! Thanks! Also, I'll take a cutting of one of the yellow sections and look for the garden centre's rose expert - I know they have one and have had good advice in the past. Not sure which day I'll go there but watch this space.

I took a sample of the rose with me to Dobbie's Cirencester. I was told the problem is probably under-watering and that roses should be given plenty of water twice a day! I'm ready to risk not following that advice to the letter, as I have other things to do in my life. I also looked for RoseClear. When I couldn't find it I asked for help and was firmly told, "We don't stock that any more, sir. It's not eco-friendly." I bought their recommended replacement plus some specialist rose feed, so I'll watch how things go.

Oh dear, I forgot to say, its now sold as Roseclear Ultra - has a slightly different formulation to the older version.