ID Much Appreciated

This beauty is growing through a patch of spuds on the allotment and not doing the nearby tatties much good.

It's a couple of weeks since the pic was taken, keep waiting for the flower heads to open for an ID but it's impossible to open them with one hand and a phone to take pics in the other.

It has four, very delicate pale green flower heads that (regrettably) only open when they can be bothered, regardless of the weather conditions. Haven't counted the number of petals inside but are very morning glory (or bindweed) in appearance and have a blue rim inside petals and are white in colour deeper inside flowers; each has 5 yellow antlers - except one flower head that's developed a purple berry?!

The plant is now about 2ft high with a stalk well over an inch thick. Other allotmenters are mystified. Any ideas what this is?

 

I think it might be this.
Nicandra physalodes (shoo-fly plant)/RHS Gardening

 

@pete - you matey are a legend - thank you very much !!!

The ID looks spot-on. Been trying to find this mysterious plant's name and gave up. It will be a keeper. There's too many tatties anyway from the former allotment tenant. And if it seeds everywhere, so what... there's so many 'wildflowers' there anyway and at least this one has a certain 'allurement' about it i.e. the hope it opens up for a display.

One nickname "apple of Sodom" sounds rather worrying though. If there are any talking snakes in the trees, time to give up allotments for good

 

It certainly will seed everywhere. Supposed to have the power to send people to sleep. Never noticed it myself though.

 

You probably aren't eating enough of it.