W11 and W8 at Wooton, Isle of Wight on May 2016. © Peter Skuce
The LB&SCR-built "Terrier" A1 locomotives were constructed between 1872 and 1880 at Brighton works. 17 of these were rebuilt to A1X class between 1911 and 1913, which involved re-boilering the locomotives as well as extending the smokeboxes, moving the placement of the sandboxes and some other changes. The class were nicknamed "Terriers" due to their distincitve exhaust note but also gained other names such as "Rooters" and "Hayling Billy". Originally working on passenger services out of London Bridge and Victoria stations, they moved to shunting and shorter passenger services after being replaced by larger locomotives.
(Information provided via Wikipedia)