Mystery Monster

I have watched this garden invader grow steadily over the summer. It has provided more and more interest as the days go by. Now at nearly 6 feet tall it towers above all other flowers nearby. I would be proud to say I had cultivated it from scratch but not the case. All I want is a name for it, then I can appear knowledgeable when I talk to neighbours and friends about it haha. Thanks for any help.
Puzzled

 

Its some kind of Mallow. Have a Google and see what you find.

 

An in focus picture of the whole plant would help, an indication of the leaf dimensions and more detailed photos rather than thumb nails would all help. The flower makes me think geranium.

 

Thanks to both for your replies. After a little research Pete I do believe it is a Common Mallow. Just browsing online I notice that the plant roots from the Marsh Mallow were formerly used to make Marshmallows a confection.
Sorry I failed to give an indication of the leaf size Pete, will try to remember next time. I did however check the thumbnails and in my browser they opened up as a full size image with a single click.