Having had to carry out a little extra research than normal into this topic, I thought I'd share the results by gathering together various links on the subject
For background information, Wikipedia has an accurate, if brief entry.
Other authoritative information is available from the church, and a Times Online article
The report on the Wallbank court case that brought this "new" risk to conveyancers' attention is a useful read - though it should be noted that the original repairs costs were relatively small; the Wallbanks built up a huge legal bill by fighting the claim tooth and nail
More detailed information is available from commercial websites but bear in mind that they have a vested interest in promoting their insurance policies