I don't know about "wrong" but it looks to me like they need harvesting. Dig one plant up and see whether the spuds are ok.

Looks to me as if you have blight. Check out Ian Digs photos as he has put up pix of blight or google potato blight. If you do have blight you need to remove the shaws from all of your potatoes now and either burn or put in wheelie bin. When you lift the potatoes make sure you don't leave any marble sized ones behind. Don't grow potatoes, tomatoes or any of veg from the solanum family there for seven years.

I have dug some of them up and they do look ready for eating, Thanks for your answers.