One of the campanulas but not sure which.
Campanula. I've loads of them too.
could it be Pritchard's Variety?
Campanula lactiflora. Mine seed around and come up in all shades of blue, violet and almost pink, like 'Loddon Anna'. Make wonderful hefty plants!
Pritchards variety is blue, which is the one in the picture. Loddon Anna is pink.
I'm bound to have it as I must have more or less most varieties as a lot of my "cool garden" is done with campanula. I tend to use it in other borders too where I want height and fabulous colour. As others have said the colour range is wide though and so I have got them planted in mixed coloured areas where "blue is banned" and there they are decidedly "pink" .
I really love them and they absolutely fill all of my criteria for a garden. If forced to choose then my favourite is "irridescent bells". It had an almost 2 tone metalic sheen to it. Regrettably though that's the one that's about past it's best and that I've more or less totally cut down. I've got it planted with some penstemon that is a similar 2 tone My Pritchard's look much more intense and almost a purple/blue than that:
Here's another photo so you can see the range in colour
I've just sown Campanula Punctata Beetroot and I hadn't thought of Campanula for that one as it looked so different from others I have in my garden. Great photos too. Many thanks!