Nicandra physaloides - Shoofly flower.

Beat me to it Meanie . . . absolutely right, and very pretty flower but beware - it seeds itself around!

Darn, beaten me too! :-)

That flower looks just like a Cobaea flower in it's infancy !

It's not though because it's a climber and yours is a shorter plant altogether.
I'm not familiar with this one at all.

This is the one that I think Salty thinks is a black physalis. You can see why....

That would make sense Beattie!

Thanks to all who identified my plant much appreciated