Kerslake was born in Exeter in July 1812, proceeded in 1828 to Bristol, and soon afterwards commenced business in second-hand bookselling in Barton Alley, together with his brother-in-law, Samuel Cornish.
Previous to the fire, in which many works of great value and scarcity were destroyed, Kerslake had amassed a collection especially valuable in its antiquarian and archæological departments.