What’s happening to the leaves on my runner beans?

OK, here’s a question for all you expert gardeners out there: from the picture, what is up with my runner beans? As you can see, the leaves are discoloured and patchy-looking. I’m assuming it’s some sort of mineral deficiency (nitrogen? phosphorus?) but would appreciate a bit of advice. If it’s relevant, the bean variety is good old Scarlet Emperor.

On a completely unrelated note, I am plagued with blackfly at the moment. They started by attacking the small comfrey patch in the back garden, and are now spreading to my tomatoes. Looks as though I’ll be out with the spray gun full of soapy water tomorrow morning.

The good news: I have two respectable-looking courgettes! Yay! Go me!