Calculating all-time rankings?

A long-time fan of the show, Ken Weavers, set himself the task of deriving an absolute measure of how well each team had performed. For example, if a team loses narrowly to the eventual champions, they deserve more recognition than to be just one of the first round losers. He thus derived an algorithm, much like that used in calculating chess rankings, in which not only the size and margin of victory matters, but also the strength of the opposition, derived in turn from their other performances.

The measure obviously relies on the fact that the difficulty of questions is consistent from week to week and year to year, something which the production team deny, stating that the questions get harder as the rounds progress, and indeed that the questions in each series are "10 percent harder than the previous series". Although, in my opinion, this is an exaggeration there is more than a little truth in it, despite a quick glance at the average points per match on the series so far.

Anyway, below is a table that Ken has provided, which gives the 25 teams from the Paxman series that have the highest ratings according to his system. They are for interest only, and to be taken with a small pinch of salt! The series winners that don't make the table are Corpus Christi, Oxford 2005 in 37th place, Birkbeck, London 2003 in 72nd place, and Magdalen, Oxford 2004 in 123rd place.

The top-ranked team in each series is as follows.