Plant identification help
 

I'm hoping this is an okay place to post this. Could anyone help identify this plant? I'm thinking some sort of convolvulus, but we're surrounded by arvensis and I've not seen any flowers like this on a convolvulus before. It sprung up very quickly in my vegetable patch and curiosity got the better of me so it got a pot rather than a place on the compost heap!

Any ideas?

http://img.photobucket.com/albums/v6...l/P1040019.jpg

http://img.photobucket.com/albums/v6...l/P1040023.jpg