How many ways can Cayley be spelt? As mentioned more than once on this site, in the 19th century some families varied the spelling of their surname between Cayley and Caley. Go back further in time, and the range of spellings multiplies, including for people linked to the Yorkshire baronets, whose surname spelling did not settle down until about 1700 (and even after that one finds some different spellings in official documents).
In the 17th and 18th centuries, among other variants we find Cailey, Caile, Cailey, Cayle, Caly, Calye, Caily, Caylie, Kayley, Kayly, Kaily, Kailey, Kaile, Kayle, Kaley, Kaly and Keyley. It is not uncommon to find different spellings in parish registers and other records for the same person. Sir Arthur Cayley (c.1615-?1698), brother of the first Cayley baronet, is a good example: his name is variously spelt Caley, Cayley, Caly, Cailey, and – if, as I believe, I have correctly identified his burial record – Cayle.
Still further back, in pre-Tudor times, in addition to all those forms we find many further versions of the name, including Cailly, Cailli, Caili, Cailewey, Caylli, Cayllie, Cayli, Calle, Calewe, Kailly, Kailli, Kaylly, Kaylegh – and even, for one set of records from the early 14th century, Kellaways, which ties in with the belief of researchers for the Callaway Family Association that at least some people with the surname Callaway, Kallaway or Kellaway (or variants) descended from the de Cailly family. (John de Cailly inherited lands from the wealthy Giffard family in 1327: he had a Giffard great-grandmother, the lands included estates in Gloucestershire, and some Gloucestershire records refer to him as ‘John of Kellaways.’)
In addition Osbern, one of the sons of the Guillaume de Cailly who probably fought at the Battle of Hastings, renounced his rights to the Cailly estates in Normandy after marrying someone who inherited estates at nearby Préaux and was thereafter known as de Préaux, giving rise to a long line of descendants with the name de Préaux (or variants on that).
This rich mix of names makes for some complex fun for those doing genealogical research.