Thank you for the nom Rosefriend,. If I manage to get some seeds from the Centaurea I will happily send you some. Thank you for your comments Ladygardener,. The Centaurea plant is a shorter plant than the blue flowered one I have (only grows to about a foot tall) and the flowers a smaller too. If you, like RF you would like to give it a try, and I manage to get seeds from it, I will happily send you some.
Thanks for the offer bagpuss, if you get seeds then yes I'd love some please, thank you very much for the offer but don't feel under any pressure. I dead head most of my plants in order to enjoy the blooms for longer and I know how difficult it sometimes is to get seeds.