Is this is silene dioica? The guy I got it from said it was lychnis viscaria but I think he got a little mixed up. It doesn't look like the pictures I found on the web.
Sue it sure looks like the pic of lychnis viscaria in my botanica book.
Here's one of silene dioica picture that i thought it could be. http://nafoku.de/flora/htm/siledioi.htm
The lychis viscaria here http://linnaeus.nrm.se/flora/di/caryophylla/lychn/lychvis.html looks quite different. The plant is fuzzy and I haven't noticed it being sticky.
We call that plant Lychnis diocia (not sure about the spelling of second part) in Ireland, and there's an old double form available too. The stems are a little shorter.
I know the stems of the Lychnis viscaria are sticky - there's also a double form of that.
I have both Silene diocia and lychnis viscaria splendens plena. L. viscaria usually has sticky stems but not all, the one we have isn't sticky. I still think its L. viscaria it may even be the cultivar 'fever' which has that great magenta colour.