The London, Brighton and South Coast Railway (LB&SCR) A1 class is a class of British 0-6-0T steam locomotive. Designed by William Stroudley, 50 members of the class were built in 1872 and between 1874 and 1880, all at Brighton railway works. The class has received several nicknames, initially being known as "Rooters" by their south London crews. However, the engines were more famously known as "Terriers" on account of the distinctive 'bark' of the exhaust beat. Later in their careers, some engines were known as "Hayling Billy" on account of their work on the Hayling Island branch line. A pub of this name on the island was briefly home to the engine which is now No. W8 Freshwater.

Brighton railway works was one of the earliest railway-owned locomotive repair works, founded in 1840 by the London and Brighton Railway in Brighton, England, and thus pre-dating the more famous railway works at Crewe, Doncaster and Swindon. The works grew steadily between 1841 and 1900 but efficient operation was always hampered by the restricted site, and there were several plans to close it and move the facility elsewhere. Nevertheless, between 1852 and 1957 more than 1200 steam locomotives as well as prototype diesel electric and electric locomotives were constructed there, before the eventual closure of the facility in 1962.