[teabags]

i have just dug up my first batch of maris piper and every potato has small holes  on the skin, there was a red ants nest by the potatoes could this be the problem if not ant other ideas

[Livinhope]

In my humble experience this is a tiny black slug.  I've actually dug potatoes with them stil in situ.

[mikem]

I would suggest that it may be wireworm.

[paintedlady]

In my humble experience, Maris Pipers have been quite susceptible to slug damage (as are King Edwards  )