Potato blight

My Setanta maincrop have been hit by blight. I have disposed of affected leaves and given them a good watering with the hope of gaining a few more days but I suspect the hulmes will have to be cut down soon. Two weeks earlier than last year.

Some leaves are beginning to yellow and new areas of blight are appearing on the foliage but there is still  greenery. I am going away for a week. Question: should I leave the foliage believing what is said about Setanta and hoping for a a little bit longer growing time or should I cut it down as there is probably not much left to gain? What would you do?

I followed your advice and cut the tops off. I have just lifted them and have a superb crop with some enormous potatoes 
I wasn't going to grow Setanta next year but now I am not so sure.