I think it might be Lychnis chalcedonica - can't quite see the detail of the flowers. There's a picture of it here

http://www.bbc.co.uk/gardening/plants/plant_finder/plant_pages/510.shtml

I agree, although the name is now Silene chalcedonica.

lychnis sounds familiar thanks

Looks very nice indeed. Does it like full sun or partial?

In theory, it likes full sun - but when I grew these years ago in full sun, they looked really poor, nowhere near as good as these do, so possibly some shade is beneficial, particularly in the middle of the day, I'm guessing. Lancs111, I'd be interested to know how much sun these ones get - and whether your soil is heavy clay or light and free draining?

Bamboo, I grow these in part shade (sun from mid- afternoon) on alkaline, stony free draining soil, they seem to like these conditions as they flower well.

Thanks Jaykaty - I've just looked them up online - they're not fussed about ph apparently, and partial shade is fine, as is full sun, so long as the soil is fertile and, that impossible description, 'moist but free draining'.

Thanks all
My soil is clay but the border had a lot of prep when i dug it.
They get the sun from about midday onwards

Well yours look so good I'm tempted to try them again...

Honestly Bamboo its had no special treatment just likes where it is
Cant claim any credit for it...though id love to!