(origin: Local) Derived from Brockles, a small town of that name in England, and by, near to; a village. Dutch, Brock, a marsh; also, broken land. In a party in which the celebrated Porson was a guest, there was also a physician by this name, Dr. Brocklesby, a descendant of the eminent man who attended Dr. Johnson in his last illness. In addressing Dr. Brocklesby, Porson called him Dr. Rock--"Yes, Dr. Rock--no, Dr. Rock," etc.--a name rendered almost infamous by Hogarth, in his picture of the "March of the Guards." At length, Dr. Brocklesby became offended, and said, "Mr. Porson, my name is not Rock, it is Brocklesby," pronouncing the syllables distinctly, Brock-les-by. "Well," said Porson, "if Brock-les-b is not Rock, then I know nothing of Algebra.

Arthur, William (1857) An Etymological Dictionary of Family and Christian Names. New York: Sheldon, Blakeman. Public Domain.

BROCKLESBY. A parish in co. Lincoln.

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