Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
LENNIE
As described in historical dictionaries
Patronymica Britannica (1860)
LENNIE. 1. A 'nurse-name' of Leonard. 2. L'Aine, Fr., corresponding with Senioi", Eld, &c., has been suggested.