Posted: 17/06/2013 at 12:06
Unfortunately, I think that the general advice will always be to dig it out. I had to do this myself last year and ended up breaking my spade in half. The only way I could do it was to get what I believe is called a 'fencer's grafter'. It is an indestructable 'spade' that looks more like a piece of scaffolding with a blade welded onto the end. It doubles up as a spade/crowbar.
I think you will struggle finding one in the usual DIY stores but it worth it if you want to keep your other garden tools in one piece.
It was still incredibly hard work and so you may want to resort to the classifieds in the local paper and get someone with a strong back. That might also solve the problem of getting rid of the roots. There will be masses of the stuff.