Sorry cannot answer that question, but have asimilar one of my own:
Planted 2 varieties of pots, early APril also,
1: Whites - Maris Piper, grew to about 3 feet, lots of flowers, all falling over now, I've dug a few small (new) potatoes, but should I leave the rest or dig them too?
2: Reds - Desiree, grown to approx 2 feet tall, just started to flower, but can see pots pushing through soil in a couple of places, they are tiny - feel I should leave these in til Aug/Sept/Oct is this OK?