Pam Moore wrote:

I understood that if potatoes are left to flower and then fruit, the
potatoes will not be so big. Once the flowers start the plant puts
its energy into making fruits and seeds.
I've never tried it, but it makes sense, I think. It's a GQT hint,
probably Bob Flowerdew.

So what does the hint say you should do? Cut the flowers off? Surely
not harvest the potatoes before the flowers appear - for anything other
than the earliest first earlies, the tubers would still be very small at
that stage.

I've left mine to their own devices to flower if they want. They're
small, but surprisingly pretty!

Peter