Two questions about potatoes

Hiya, I have a couple of quick potato questions:

Question 1:
the above-ground growth on some of my maincrop potatoes has really died back in the last few weeks. I wondered if they should be dug up, or if they are likely to keep growing down below/will be ok in the ground.

They are desirees, planted on the 17th of April, in the south of england, into ground that had squash in last year, and prior to that nothing but comfrey and brambles in 10+ years. The topgrowth has been pretty impressive - 3ft maybe or so, and there have been a lot of potatoe-tomatoes, or whatever you call them.

They're on the LHS of this pic, it's a bit hard to see, but they're yellowing, and a bit colapsed, whereas the PFAs on the right are still green and fairly upright.


Question 2:
Both my first earlies (arran pilots) and 2nds (Charlottes), planted into ground as above, in early april, have given really large potatoes - typically a decent yield, although not massive, but concentrated in relatively fewer big potatoes (like big baker sizes) rather than lots of smaller ones, as i would expect for earlies.

Is this just luck of the draw, or is there some potential reason for it? The Arrans were harvested mainly in june/july, the charlottes have been coming up since mid july.

Thanks in advance for any advice.

I'm just echoing Salmo's advice and to say that we also had some very large first earlies from Arran Pilot --- quite a surprise 


And I shall keep a close eye on my PFAs which are one of my favourites and I should be sorry to lose the crop to blight