They seemed perfectly healthy. We have just come home after ten days away and the leaves on my first crop are going brown. Does this just mean that they are ready or have they got a terrible disease? The second crop are fine (they are flowering). We ate some from the first crop yesterday and they seemed okay.
If you planted earlies or second earlies, they may well be ready about now to harvest and the foliage die back is a sign of this. Different varieties mature at different times, i.e. you could have 2 different varieties of second early potatoes and they would mature at a slightly diffent time from each other.