What is this ?

It's a Centaurea (montana) , Mazziestar, google it and you'll find lots of images and info :-)

Blimey, that was quick! Thank you,.... these were growing in a derelict garden so I'm assuming they are wild flowers? ( I'll google them)..

I have several types in my own garden, i think they're gorgeous :-)

Yes they are, like something from outer space! I shall try to acquire some, especially if they are perennials..

Yes they are perennials. Do try to get some. They're beautiful.