Last updated at 12:24 AM on 01st July 2009
William IV: Illegitimate daughter was ancestor of David Cameron
It is the bible of the aristocracy... and has barely changed over the 173 years since it was first published.
But Burke's Peerage and Gentry is finally succumbing to the demands of the 21st century.
The guide, which lists the genealogy of every royal and aristocratic family in the Europe and the U.S., is to include illegitimate children for the first time.