Plant ID please - are are these beasts?

Hi there again - sorry, two posts at the same time! (can you tell I've just come in from the garden?!)

I have a enormous THING in one of my flower beds, as below. Can someone tell me what it is? My main problem at the moment is that it patently needs tieing and supporting, but it's flipping spiky and hard to get at - I need a biohazard suit I think! 

Obviously I appreciate you can't help me with the tieing up thing (although you're all welcome to pop round and assist if you like...) but knowing what I'm dealing with would be a start!

Thanks!