Black spot. Spray with Rose fungicide.

Hi,

As Owdboggy says it's a fungal disease called Black spot. As well as spraying, it's best to dispose of infected leaves. Make sure you repeat the spraying application as per the instructions.

I hope you're able to resolve the issue.

Tim

Next year best to spray with a combined inseceticide and fungicide as soon as it comes into leaf before you get it as a precaution rather than after. May have to spray throughout the season.