The older Thornton Heath, part of the Manor of Norbury, had been open heath common land for centuries. Its main claim to fame was the useful pond, for horses and cattle, and the gallows, which stood on the site. The Enclosure Act of 1799 turned it into privately-owned farmland. The Enclosure also enabled owners to sell their land for development, and within a few years there was a fair cluster of buildings around the pond area and development (mostly quite substantial houses) was spreading up the eastern side of the London Road on the way to Croydon.

As already mentioned, 'New Thornton Heath' was created by the railway. Before 1862, the area had a few farmhouses, one or two villas and, an important local industry, market-gardening. These were soon engulfed by new streets. By 1900 there was very little open land left in Thornton Heath, new or old.

At the junction of the High Street and Parchmore Road, on a site previously called Walker's Green, stands the Clocktower, which was built in 1900, financed partly by public subscription. In earlier times, Croydon was well-known for its charcoal-burners or colliers, and Colliers Water Lane commemorates this connection with that trade. Another industry connected with the area until recently was clock and bell-making. The world-famous firm of Gillett & Johnston was based in Union Road from 1844 to 1957, and its clock tower was a well-known landmark in the area until it was demolished in 1997.