BILL did not come into vogue as a short form of William until the 19th century. The Irish may have influenced this when they referred to William the Conqueror as King Billie. (It just took a long time to get to England.) The change of �w� to �b� is thought to have come about because of the difference in the pronunciation of consonants between the Celtic language and the Germanic languages, which pronounced the �w� as a �v�. The Castilian Spanish pronounce �v� as a �b� even today.

As a surname it is generally a short form of some Germanic compound names such as Billiard. It can also be an occupational name for a weapon maker who specialized in swords or halberds and later for the makers of agricultural tools like the scythe and pruning hook; all come from the Old English word bil meaning sword.

In some instance,Bill can be a personal name handed down from the surname and have nothing to do with William.

To confuse things even further, a surname like Billson or Billings can be a patronymic from the non-William Bill, but not always so.
There was, at one time, a tribe called the Billingas who probably got their name from their first leader, a man called Billa, a very old, pre-Roman name of ancient Britons. This name probably derived from an ancient goddess called Bil who was a minor deity in Scandinavian mythology (a child who was flung up to the moon). There was also a dwarf called Billingr in Teutonic tribal epics. (9) page 89.

Researching: George H. Billson m. Ester A. Askew � Newton 1892.