3 potatoes

Is it the lack of sunshine that has caused our early potato crop not to flower?

Should we lift them now even though they haven't flowered?

Do we continue to wait for them to flower?

If we leave them longer will the wet conditions rot them before they are harvested?

We lifted one to see if it would give us a clue and it had three good sized potatoes and lots of wee ones which makes me think we should leave them a bit longer.

Although we have grown potatoes before the last time was more than 20 years ago (I am ashamed to say) so we are really treading on untested ground.

A friend who decided to grow her own potatoes last year had a bounteous area of wonderful dark green foliage and lovely delicate white flowers which she harvested and got only 1 potato - Yes that is not a typo, 1 potato - so we are already two up on her crop.

Google hasn't helped so hopefully somebody out there can point me in the right direction.