I think it's Cerinthe major purpurescens. I fell in love with it when I first saw it in the Which experimental gardens some years ago.

I wonder if it's frost hardy......

Sorry, don't know what it is but it's lovely

yes it is Cerinthe major purpurescens. as far as I am aare they are not hardy in yorkshire but they may be ok further south. the self seed freely however.

Many thanks it is so pretty I saw it on an allotment so will now try and get some seeds. Thanks again.