There is a small amount of blight just starting on some of the plots, but i first spotted this problem a couple of weeks ago.
I Dug up some international kidneys and they had white spots on the tubers that were easily wiped off. It didn't seen to affect the flavour at all.
Two weeks later, when I was digging up some more, lots more spuds affected and I could smell potatoes rotting in the ground!!!
I wondered if it is just rot from water-logging? AS my plot is on clay and has been very wet. Does that happen rather than a disease as such?
I cut all the greenery off anyway and will try and lift some more spuds after this weeks sunshine dries the ground out a little.
Sounds like swollen lenticels, due to wet growing conditions. Nothing to worry about. Try the link below, page 9.
http://extension.oregonstate.edu/catalog/pdf/em/em8948-e.pdf