Suggestions on UK rose leaf concern?

A close relative in Surry UK is asking if l know whats wrong with the leaves on their Ancient Mariner. Never seen this in my garden … its only predominate on underside from edges. Anybody have suggestions what it could be?

“Tx … “ “ The weather has been very cold in the last few weeks and fairly damp. Our garden is southeast facing so this rose gets sun first thing in morning and then a fair bit of shade for the rest of the day. It’s David Austin’s Ancient. “
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Soil to start was builders rubble with lots of rocks (new build-1 year) and very clay rich- has been adding top soil. Wet feet?

Likely frost burn … temps below 0C a couple of times

I think some of my rose leaves look like that. I am in the UK too and up until very recently we have had temperatures dip to below 0 degrees Centigrade (freezing point of water) at night most nights. Today was a beautiful sunny day, and maybe the past week night time temperatures haven’t been so cold. Summer has been slow arriving this year in the UK.

Txs for the advisement and relaying your spring experience this year.