He was born to Daniel Watney (1771–1831) of Mitcham, Surrey and Mary Galpin (1771–1830), daughter of James Galpin (died 1789) of Mitcham, Surrey. He was the grandson of John Watney (1747–1814) and great-grandson of Daniel Watney (1705–1780) of Wimbledon, Surrey.
The Watney family were the main partners in the Stag Brewery of Pimlico for much of the 19th century. The brewery was known as Elliot, Watney & Company from about 1849. He finally retired in 1858 and the firm became known as James Watney & Company
James Watney then kept the management almost entirely to himself until his death, at well over eighty years, in 1884.
After his death in 1884, Watney & Company Limited became a private limited company in 1885. In 1898, it acquired Messrs.
Combe Delafield and Company and Messrs. Reid and Company, and was thereafter known as Messrs.
Watney Combe & Reid. James Watney was Master of the Mercers" Company in 1846, but had few other interests outside business.
James Watney contributed several thousands of pounds towards building a new church just as his father had done at Mitcham.
