It looks like a Datura, or other name is Brugmansia.
Google it and you'll get numerous images and information about it.

Yes, it's an annual weed called Datura stramonium or Thornapple. Toxic in all parts as all Daturas are.

I kind of like it, then I also like bindweed...in someone else's garden though :-)

Pimpernel - if you want I should be able to send you some seeds for D.metel.............

http://www.growsonyou.com/garden/show_garden_item/27653-datura-metel

and possibly D.wrightii............

http://www.growsonyou.com/garden/show_garden_item/34043-datura-wrightii

Louise - Datura and Brugmansia are separate species, although they are the only two members of the Datureae tribe, which is a part of the Solanaceae family.
As a rule of thumb, Brugs are taller growing with pendant flowers, whilst the Datura typically grows up to about a metre and has flowers that point upwards. The blooms of both are pleasantly fragrant.

Thanks Meanie :-)

Louise = I was worried that I may have been a little too "preachy", as I am a little evangelical about Datura........
The great advantage in my eyes of Datura over Brugmansia is that it is a viable and reliable annual which I grow from seed sown in January/February.

Meanie, not at all !
It's good to learn :-)

If you ever want to try one PM me - I should have plenty of seeds, unless we get a really early frost.