Ivan: this Bill relates mainly to instances of life peers who have either committed serious crimes or otherwise brought the system into disrepute through their behaviour (the prime example of the latter, in the minds of those supporting this bill, being Lord Mandelson). There are already laws allowing members of the House of Lords to be suspended or expelled; however, they retain their titles. The idea is that peers could also have their titles removed, so Mandelson would revert to being Mr Peter Mandelson. As S. S. points out, this usually requires a specific Act of Parliament for each peerage removed, so the question is whether a general Act could be passed so that a simple process can then be used to remove a title.
It is not clear whether this is intended to apply also to hereditary peers. I suspect not, as hereditaries will no longer be in the public eye, so I am expecting the Bill only to apply to life peerages, but we shall see.