Miss Willmott's Ghost.

This is Eryngium giganteum, a form of Sea Holly.
It is a tap rooted, short lived herbacious perennial. It grows to about 3 feet high and where this was taken has formed a large clump several feet across. It looks rather splendid.

Ellen Willmott was a nineteenth century gardener with a sense of humour. Whenever she was invited to other gardens she would wait until the owner was looking the other way and would scatter the seeds of this plant in likely areas.
In the following year this striking sea holly would appear. Eventually her friends guessed where the seeds were coming from and the plant became known as Miss Willmott's Ghost.