Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
SINNOCK
As described in historical dictionaries
Patronymica Britannica (1860)
SINNOCK. A corruption of Sevenoaks, CO. Keiit. For the story of Sir William Sennock or Sevenoke, see Lambarde's Peramb. p. 520, and Eng. Surn. ii. 119. See also Snooks in this Dictionary. The H.R. present us with a Sinoch, demanding another etymology.