Designed by William Stroudley the London, Brighton and South Coast Railway built 50 class A1 0-6-0 tank locomotives between 1872 and 1880 for London suburban passenger service. The sprightly engines became known as 'Terriers' to commuters and enthusiasts from the sharp bark of the exhaust. Soon displaced from their original duties the Terriers found other work, many branch lines benefiting from these quite new engines with some sold to other operators, including the SE&CR, LSWR, the Isle of Wight railway companies, K&ESR and WC&PR light railways and the Newhaven Harbour company.
17 of the class were upgraded with new boilers during their working lives, becoming the A1X class and the last Terriers were not withdrawn from British Railways service until the closure of the Hayling Island branch in October 1963. By this date two Terriers had already entered preservation and 55 Stepney had hauled the opening train on the Bluebell Railway. A total of 10 have been preserved, most having been restored to service on heritage railways with 4 being operational during 2017.
The Dapol O gauge model has been created from a detailed laser-scan of W8 Freshwater on the Isle of Wight steam railway. A great deal of attention has been applied to the detail changes made to these engines over their long lives, with the tooling being designed to allow for both the original A1 (with smokebox wings) and later reboilered A1X class (with longer smokebox) to be produced. The cab has been kept completely unobstructed allowing for full internal detailing, ready for the crew to board! In addition to the chassis the running plate and wheels are die-cast to increase the weight while a skew-wound 5 pole motor is installed to provide smooth torque at low speeds.