Artichoke Thistle

I found this 6ft high plant in the park.

My first thoughts were that it was a giant thistle, but after a little research I think it's a Cardoon, or Artichoke Thistle (Cynara cardunculus). Perhaps someone will tell me if I'm wrong.

Apparently it's edible, the flower buds being eaten like an artichoke, and the stems can be braised.