Not Sure (Leaf problem)

Hi there, I am not at all experienced at growing roses, but I have three in my garden which I have been given as gifts, and which are of sentimental value. This particular rose (don't know what it is but it is very thorny indeed, has a dark red flower, and a wonderful scent) has developed pale 'freckles' on some of the lower leaves, as shown in my not very good photo. The bottom of the rose is very bushy, so I have thinned some of the leaves in order to let air in, although I have no idea whether that will help.

 

Thank you, @wiseowl. Super advice as always. I have been spraying the hose over the leaves , but will stop that immediately.