The vacant post of under warder was advertised on 21 September 1860:
LINCOLN CITY GAOL.
UNDER TURNKEY WANTED.
WANTED,an active Single Man as UNDER TURNKEY, at the Lincoln City Prison. Applicants must not be above 35 years of age. Salary £40 per annum. Furnished apartments in the prison, and coals and candles allowed...
I can't find a report of Willit's appointment but there is a mention of his subsequent resignation and replacement:
"A young man named Waller, from Collingham, was yesterday appointed turnkey at the city gaol, the place of Willet Ball, resigned. There were nine candidates." (31 May 1861)