All the potatoes I put into store last year, have been sprouting for some
time now, whilst it doesn't seem to stop me eating them, it's a nuisance to
find when I go to bring them into the house that I'm having to pull off
sprouts 3 or 4 inches long.

They are stored in boxes, covered with sacking, so no light can get in.

So, is this common, or am I doing something wrong?

The potatoes in the supermarkets don't seem to have this problem.

Alan