According to Bulmers 1890:-
The Mechanic's Institute, built in 1848-9, by the late Sir W. Payne Gallwey, was amalgamated with the Church Institute about four years ago, and is now styled Thirsk Institute. It contains, in addittion to a well stocked library, a large lecture hall, capableof seating nearly a thousand persons. Art classes are held in the winter months..
Bulmers lists John Pennington as the art teacher involved.
Kelly's 1879 directory mentions the mechanics institute as well as the church institute, and its secretary - though it gives a slightly different construction date.
Henry Smith was a vice-president of Thirsk Institute - his brother Reginald was probably the president at the time.
The Mechanics Institute was on the corner of Westgate where the Ritz Cinema now is.