From the IGC:

Thomas Southgate
1885?-1909

Thomas Southgate may have been in business with Mears as Southgate & Mears before he was recorded in business on his own account at 6 Burton Crescent in 1896. He was certainly apprenticed in London, possibly to James Woodward.
In 1876 with James Woodward Jnr he took out two provisional patents for self-cocking hammerguns (Nos. 117 and 600).

At some time he became an outworker, he worked as such for Holland & Holland, but at what dates is not known.

In 1880 with Edward Harrison and James Lang he patented a back action lever cocking hammerless mechanism (No. 278).

In 1884 with Joseph Lang he patented a drop-down action with closing cocking and safety sears (No. 4458).

In 1884, but only in that year, a firm named Southgate & Mears was recorded in Wardour Street, this may have been Thomas Southgate.

On 16 February 1889 he patented an ejector mechanism using over-centre tumblers (No. 12314), this was the famous "Southgate ejector" (the basis of which was Thomas Perkes patent ejector 1968/1878), and in 1890 improvements to it (No. 662). He registered another patent in 1890 No. 6723(?), another ejector patent in 1893 (no. 8239 using two cocking levers), and in 1903 (after Beesley's ejector patent expired) yet another which modified his own 1893 patent by using only one cocking lever.

In 1908 he moved to 6 Cartwright Gardens.

He was not recorded after 1909.

In 1891 Thomas took on an apprentice named Charles Cooper. Cooper remained with him after his 5 year apprenticeship ended, but in July 1904 he was made redundant due to "the slackness of trade".

Pete