Richard Allan has a great solution to this problem:
What this is doing is forcing Parliament to look at how it handles other people reproducing the material on the Official Parliamentary Website. It would look awful if Parliament were to try and stop people from using what is and should be public information. But the public interest would not be served by people of dubious motives giving false information by doctoring the official record.Link (Thanks, Tom!)
What is the answer? Perhaps a Creative Commons license for the House of Commons which can allow re-use of material without payment but subject to conditions such as repetition in full without alteration? I am starting to think there is a good campaign here to ask Parliament to use appropriate Creative Commons licenses for all its output?