In 1856 Frederick Edward Blackett Beaumont, a Lieutenant in the Royal Engineers, was granted a patent for improvements to the Adams revolver. This enabled it to be be fired after first cocking the hammer, as in Colt single-action revolvers, but for subsequent shots by merely pressing the trigger. It was the first true double-action system 1 and was adopted by the British Army later in 1856 and subsequently by Holland and Russia. Approximately 1,750 of the revolvers, manufactured under licence by the Massachusetts Arms Company, were purchased by the Union Army at the beginning of the American Civil War.
Frederick Edward Blackett Beaumont was descended from the Blacketts on both his mother’s and his father’s side, and was the 1st cousin of Wentworth Blackett Beaumont (see An engineering achievement). He also invented the Beaumont tunnel boring machine, which was used in the construction of the Mersey Railway Tunnel in the mid-1880s, and was associated with the Channel Tunnel Company. He sat as Member of Parliament for South Durham from 1868 to 1880.
1 Link to Wikipedia article.