I have never seen an Eryngium that tall, the biggest of which I know is E pandanifolium which gets to about 6 feet.
I do hope you mean Echium pininana

Mind, if the eryngiums do grow that tall, how big will the echiums be?!
Echium maritimum grows to about 3ft (90cm), and E. pininana up to 12ft (4m). So, what plant do we have here?

Odd. Kizibu's posting was about Eryngium
http://www.growsonyou.com/question/show/2689-does-your-sea-holly-stink

Well done Owdboggy-i have loooked up the echium pininana and that is the plants in my garden-
Thank you very much and now I have seen the spread ( to 90cm) all I have to do is try to move the first and original plant which is just at the bottom of my steps into the garden.
Thank you for your comments

I am not sure it is possible to move them and for them to survive. Certainly the once we have (never have been able to id it) has a tap root which if damaged means the whole plant dies. Found that the only way to get it elsewhere in the garden is from sowing seed directly where I want it to grow.