Hi Salty, ive googled Black Physalis, and only orange chinese lantern comes up, maybe you have got a rare plant in your garden. Looking forward to seeing your pics..

thank you daisy,
i work for the council as a gardener. i came across it on wasteland.last year, grew it on at home, and kept the seeds. the planted this year, and the bells are just showing. and they are black.

Have you had a look at the "lanterns" on Nicandra physaloides as I suggested Salty? They were very frequently found last year on waste ground & I think that may be what you have.

Ah, I think that Beattie may have struck gold, or black, with that answere.