Most of these suggestions fail to convince because of a doubt as to how a surname arising perhaps about 1300 could derive directly from a word or name, used or 'rare' some centuries earlier - or from a conjectural sept from perhaps as early as the sixth Century.
Connection with Northamptonshire and Oxfordshire KITTE families seems unlikely, and John CHYTTE of Somerset (1327, 'Kirby's Quest') is rather far afield, but William CITTI of Highclere, Hants., in the 13th century and John Le CHIT of Godalming, 1274, are nearer home.
It was the Rev. W. W. Capes in his 'Scenes of Rural Life in Hampshire among the Manors of Bramshott' (1901) who suggested Ciltelei, Chiltelee or Chiltley, one of the five ancient manors, as the origin of the name. He tells us that this very small manor had four tenants and two plough teams and was kept as a royal manor, dispossessing the freeholder Lauch. 'In the 13th century a family which took its surname from the manor was in possession of it, and was mentioned from time to time in the Court Rolls of Bramshott, or as representing the parish at Winchester, when the income of the year was officially registered. They disappear from view soon afterwards, though possibly they lingered on for centuries in humbler state under the name of CHITTY'. The Victoria County History names William de CHILTELE, 1346, holding the 18th part of a Knight's fee, formerly John de CHILTLEY's, and seems to place the family's ownership of the Manor between 1316 and 1387. In 1898, Chiltley, 48 acres, was the residence of Mrs Tristra in the hamlet of Liphook and the ancient parish of Bramshott.
Unfortunately, the most eminent philologist who has considered this derivation is somewhat sceptical. Professor A. H. Smith, O.B.E., D.Litt., F.D., of the Department of English at University College, London, very kindly gave me his opinion in February 1967 that the suggestion 'that CHITTY is a local vernacular development of Chiltley is possible, but' (he continues) 'I should hesitate to say that it is probable, except for localised provenance of the surname in the neighbourhood of the place. I have been searching for parallel phonetic developments, but I just cannot readily lay my hands on any. But the loss of one of the 'l' sounds is likely enough, giving CHILTY or CHITLEY; it is the loss of both 'l's' which complicates it. I think the only thing that [would] prove beyond all doubt your view is the use of forms like CHILT(E)Y or CHITLEY or CHITTY as variant spellings of CHILTLEY in the surname of a single individual in the family (the Feet of Fines in the 16th century, as you know, often give all the variat spellings of the surname of an individual), or if in the spellings of the place-name Chiltley in Hants similar variants are found. Unfortunately I do not have any Hants material available especially for the 16th and 17th centuries when such developments are likely to have taken place.'