This time the result was more decisive than with the other varieties. Although it's not particularly obvious from the photo below, the pot with two seed-tubers was the clear winner.
The yield from the 2-tuber pot is at the top of this photo
The 1-tuber pot yielded 1.356kg and the 2-tuber pot yielded 1.686kg.
In view of the prolonged hot dry spell of weather, I think this is OK. I normally reckon anything over one kilogram per seed-tuber is a good result. Of course, these "Nicola" ones have had longer to develop than the other varieties, so in a way you would expect them to produce a better yield. Actually, although I have not put this to the test, I have heard that "Nicola" keep fairly well in the ground even after the haulm has completely died down, so presumably I didn't need to rush to harvest them. Having said that, I know that the skins of older potatoes can be a bit rough, and the flesh tends to be denser.
I find that "Nicola" is quite similar to the more well-known "Charlotte", which it closely resembles. However, I think that "Charlotte" is still superior. The texture is always so light and buttery - and it cooks really quickly. "Nicola" is good, but not that good.
In amongst this batch of potatoes I found one that had already started to sprout:
Presumably if I had just left it in the ground, this one would have begun the growing-cycle all over again - maybe producing spuds for Christmas?!
For the record, these are the full results from the comparative trials:-
Variety 1-tuber pot 2-tuber pot
Annabelle 628g 1237g
Juliette 863g 1103g
Charlotte 1182g 1048g
Nicola 1356g 1686g