Thornley is a quite pictureque hamlet situated between Tow Law and Wolsingham in a conservation area on a no through road but approximately a quarter of a mile off the A68, with good access to Durham, Darlington and Newcastle.

The earliest reference to Thornley is 1070-80 but the earliest buildings in the village date to about 1700. Some were originally single-story buildings with second floors added at a later date. The original school, now a private dwelling was built in 1824 but used as the school masters house after 1845 when a larger school (now the Village Hall) was built to accommodate 70 children.

An early coal mine was recorded in 1569 but the main growth of coalmining was in the later 18th and 19th centuries when it became a thriving village with a church, a school, a shoemaker, a builder, a blacksmith, a butcher, a joiner, a shopkeeper, and a publican,

St Bartholemew's church, originally a chapel for the nearby church at Wolsingham was built in 1838 and enlarged in 1842  to give a Gothic appearance. The altar rail, given by the congregation in 1865, is made of the local Frosterley marble, as is the font, which was found broken in a Wolsingham garden and repaired before being installed. In 1891, the tower, octagonal steeple and outer door were added.