Originally Posted by Howie

Were the bracts white?

If so my guess is Eryngium giganteum 'Mrs Wilmott's Ghost' or Eryngium giganteum 'Silver Ghost'

It's a biennial (often taking three years to flower.) Once it is established it seeds itself everywhere, often in the cracks of paving.

Not difficult to establish from small plants. Best to buy seedlings and wait a while for the first flowers. I remember buying my first ones from the shop at Great Dixter.