I agree with Emrys. I don't know where you are in Yorks, but when I lived there I was on clay, which is virtually un-sieveable. If it is a clay subsoil, you should be able to pick out the really claggy lumps by hand as you level the ground. If it's a big garden, you may need a mini skip to get rid - I wouldn't try to bury it as it doesn't drain and it is very heavy.