Mystery plant

Hi there,after doing gardening for over 20 years its not often i find a plant i hav'nt seen before.the plant in question must be herbacious as it was;nt there a few months ago.It is now about 6ft high and has the most ferocious spines down the centre of each leaf,it must be sending suckers up as the lawn is covered in little ones,its quite ornamental but has me stumped what it is.Any ideas.

It sounds like some kind of thistle to me or perhaps Teasel.

Here's a pic of teasel. The lower spines are quite wicked.

http://www.haworth-village.org.uk/nature/pictures/large-insects.asp?pic=65