Looks like Nicandra phsalodes. Common name shoo fly. http://www.google.co.uk/images?q=ni...&source=og&sa=N&hl=en&tab=wi&biw=1239&bih=528
Silver surfer is right, it's the shoo fly, it's also called Apple of Peru, maybe you heard of it by this name.
Thanks to Silver surfer and Treesrgood you have put my mind at rest it was realy bugging me Everyone I asked was totaly baffled, it is possible it came out of the bird feeder which is near by, i know it is said to be an Annual but hopefully I will get some more plants from the seed, it has certainly brightened up a patch which I keep totaly for spring flowers Thanks again what a great site Regards Stephany
Stephany - it will produce a tomatillo type fruit, but only feed them to people you DON"T like. They are toxic to my understanding. This whole family of plants "Solanacea" is lovely. Some are delicious and some will make you ill. ;)) barb
Here is a batch on information on your Nicandra. barb http://www.ces.ncsu.edu/depts/hort/consumer/poison/Nicanph.htm