As described in historical dictionaries

Patronymica Britannica (1860)

REACH. In the South, means a creek, and sometimes a part of a river more than usually straight. A Scottish family-name of the same orthography is jironounced as a dissyllable, with the ch hard, He-ach, and is referred to a Celtic origin. A gentleman dining in a mixed company with one of the pi-oprietors of this name, whom he only knew by his writings, naturally enough called him IMr. Reach {ck soft), and was corrected with the observation, that ch should be sounded like k. " I beg Mr. Re-acli's paixlon," promptly replied the offender, "and as he is presiding over the dessert, I'll just trouble him to send me a jje-aekP''

Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.


BritishSurnames.uk is a Good Stuff website.