Picture posting is enabled for all :)
what was the soil type like and did you manure at all and can you say where you bought the seeds from
Pelleted chicken manure has a fairly high calcium content (usually about 8%). One of the effects is to make the boron in the soil unavailable to the plant, as well as contributing to scab in susceptible varieties.I still go for boron deficiency symptoms. This does not necessarily mean that your soil is deficient in boron, merely that you may have made it unavailable. Boron is also not very soluble, and the effect of the summer drought would have been to exascerbate any calcium induced deficiency.
I won't add pelleted chicken manure next year then! What sort of fertilizer do potatoes grow well with? How about the potato fertilizers by Thompson and Morgan or Organic Gardening Catalogue?