With time, surnames often change spelling and /or perceived pronunciation due to number of factors e.g. local dialect and variations in spelling given by church officials and other record takers. Up till the 20th century it was common for many folk not to read or write, so their details were passed to officials by word of mouth and the resulting written record was often down to the interpretation of the record taker. As a consequence of this, names "evolve" or "mutate" and variant forms may occur. This process may be compounded with the transcription of records resulting in further "errors" - in the case of my Richford branch my Great Grandfather William Richford doesn't appear in the 1881 census index under Richford, but is indexed under Rickford!
The Richford name may be derived from the name Rochford and be associated with a place name origin e.g. Rochford, Essex, Rochford, Herefordshire/Worcestershire, Stoke Rochford, Lincolnshire and/or Rickford in Somerset. If you say Richford out loud and vary the intonation it is very easy to arrive at a range of spellings of possible name variants. This subject has been covered at great length in a number of books1, 2, 3 and genealogical magazine articles4, 5, 6, 7. In the case of Richford there is plenty of scope to derive a number of name variants and this then begs the question which came first and which are typographical variants of the same name or distinct names in their own right with distinct regional or other origins.
Several systematic approaches have been devised to generate lists of possible name variants. These include Soundex and Metaphone and more recently NameX.
Below is the NameX list of possible variants for Richford. As an aid to to determining possible relationships between these names I've plotted the English distributions based on the The British 19th Century Surname Atlas produced by Steve Archer
1. The surname detective - Investigating surname distribution in England, 1086-present day.
Colin D. Rogers, Manchester University Press, 1995. ISBN 0 7190 4048 5
2. Family Names and Family History.
David Hey, Hambledon and London. 2000. ISBN 1 85285 255 0.
3. Searching for Surnames - A practical guide to their meanings and origins.
John Titford, Countryside Books. 2002. ISBN 1 85306 765 2
4. With Surname Atlas a picture tells a thousand words. Howard BenBrook, (2003). Journal of One-name studies, 8 (4), 13-15
5. Surname Atlas aids my theory on great-grandma's family origin. Roy Stockdill, (2003). Journal of One-name studies, 8 (4), 16
6. The pleasures and pain of deciding between variants and deviants.Roy Stockdill, (2004). Journal of One-name studies, 8 (5), 5
7. Many surname variants are really misspelt deviants. Derek Palgrave,(2004). Journal of One-name studies, 8 (5), 6-9