Huge thistle

I am about 5ft 7in but this was above my head - never seen such large thistles. The heads were about 8in across so far as I could estimate, (not being able to bring it down to me in case I broke it off). They were growing beside the entrance to a garden centre, but I didn't see any for sale inside so don't know why they were there. Extra pic is a different head - bluer colour and more compact - perhaps just not so fully open.