The locomotives were built in four batches, each by a different builder, with variations between them, noticeably in the size of the saddle tank.

Five locomotives built by Rothwell and Company with 1,100-imperial-gallon (5,000 L; 1,300 US gal) gallon saddle tanks and 18-foot-4-inch (5.59 m) wheelbase.

Four locomotives built by Beyer Peacock with 1,280-imperial-gallon (5,800 L; 1,540 US gal) saddle tanks and 19-foot-5+1⁄2-inch (5.931 m) wheelbase.

Six locomotives built by the Avonside Engine Company with 1,440-imperial-gallon (6,500 L; 1,730 US gal) saddle tanks and 18-foot-4-inch (5.59 m) wheelbase.

2051 was withdrawn following a fatal collision at Norton Fitzwarren railway station in Somerset while working a special ocean mail train from Plymouth on 11 November 1890.