One-sixth of the population of England and Wales live in the London area, and a high proportion of the population has always lived in London. Most genealogists, therefore, will have, sooner or later, to tackle the tracing of London ancestry. Many, one suspects, give up, and seek easier lines – and it is difficult to blame them. However, tracing London ancestors is not impossible, and relies on much of the same techniques used elsewhere, although with different emphases. The purpose of this booklet is to review these techniques in the specific circumstances of London.