Reigate

From Middle English Reigate, Raygate, from an unattested Old English bare‐stem compound (West Saxon *Rǣġegatu or Kentish *Rēġegatu), from Old English rǣġe (“roe deer”) + gatu (“gates”) (plural of ġeat). See ‐gate. The modern pronunciation with /aɪ/ is the result of a phonological shift during the Early Modern English period, for which two primary pathways are proposed: * It may reflect the local Kentish or South‐Eastern dialectal development of the Old English compound (*Rēġegatu). In these dialects, West Saxon ǣ was regularly raised to ē. The palatal glide of the first element vocalized, creating a diphthong that smoothed in Middle English into the long vowel /iː/, which subsequently lowered to /aɪ/ via the Great Vowel Shift. * Alternatively, descending from the standard West Saxon form (*Rǣġegatu), the Old English sequence ǣġ regularly yielded the Middle English diphthong /æi̯/. This later underwent a dialectal centralisation to [əi] in a stressed open‐syllable environment, merging with the outcome of Middle English /iː/ and eventually lowering to /aɪ/.

来源：wiktionary