Located in Derbyshire, England is the county town called Matlock. The history according to Wikipedia is that Matlock was a former spa town. Matlock ( from the Old English for Moot Oak) lies on the River Derwent, and has prospered from both the hydrotherapy industry and the mills constructed on the river and its tributary Bentley Brook. It was an unimportant collection of small villages — Matlock Town, Matlock Green, Matlock Bridge, Matlock Bank — until thermal springs were discovered in 1698.
The population increased rapidly in the 1800s, largely due to hugely popular hydros being built. At one
stage there were around twenty hydros, most on Matlock Bank. The largest was built in 1853 by John Smedley. This closed in 1955, and re-opened in 1956  as the headquarters of the Derbyshire County Council. Matlock is also home to the Derbyshire Dales District Council as well as Matlock Town council.
The Matlock Surname
It isn't unreasonable to suppose that those who were and are born with the surname of MATLOCK should originate from the early inhabitants of the place known as Matlock in Derbyshire, England.