potatoes going to mush when cooked

Hello

New to this site so don't know if this is a common problem or not. I've certainly never heard of it before. Some of my crop of first and second earlies are turning to mush in the pan when boiled. If they still have their skins on the skins just split and then they turn to mush.

It happened with a smaller crop I had last year (first year on the allotment) and I can't help but wonder if the ones it's happening to now are some that got left in the ground to sprout again. I have since found out that you aren't supposed to plant potatoes in the same place the following year, so please don't tell me off for that!