Hi Ian, I don't think blackspot actually damages the plant but of course, it does look unsightly. If it's a new plant I guess it's quite small? Pick off and dispose of all affected leaves and don't put them in your compost heap!
Good luck with the roses. I hope they make a lovely show. They will need pruning each year, however, and that is quite time consuming, I find!

Pick off the infected leaves as Penny says. As soon as you get them planted, it won't hurt to give them a spray with Rose Clear. Even if they aren't all sprouting it will kill any over-wintering black spot spores.

Hi Ian I always use cornmeal on mine a hand full once a month from now till autumn. The cornmeal is what you can get from an Asian shop it's what they make bread from

Thanks Jimmy, Kenny and Penny your tips all taken on board and hope I get a good show, thanks to you all, Ian