I broke the bath drainage pipe. How do I fix it?!

[DiscoJustice]

I was unclogging the bathroom plughole last night, and managed to, err, break it. I was screwing the silver... ummm... bit (I'm not sure what you call it, the bit of the plughole you can see normally) and I guess I screwed it too tightly. I heard a snap and it became loose. I pulled it out again and realised that the part I was screwing into had come off the pipe and was just sitting on the screw. Here's a picture which should hopefully illustrate much better than I can.
IMAGE: http://www.optibrain.co.uk/optistuff/Image086.jpg
You can see at the top of the screw an extra bit which came off from the drainpipe's screwhole.

And, just to clarify (although it's a rubbish image) this is an image of the part that's broken. You can just barely make out the three plastic struts with the screwhole in the middle. The actual screw part of that has come out.
IMAGE: http://www.optibrain.co.uk/optistuff/Image085.jpg

Will I need a new section of pipe just for that little screw bit? I'm really hoping not, the previous owners decorated the bathroom, and seem to have left no way to actually get at the underside of the bath without dismantling pretty much everything around the bath.

[peter the plumber]

You just need a new waste, there about £10

Take your old one down to a plumbing shop and get a replacement.