[2] Fifty were built to the design of George Whale between May 1906 and April 1909, being a tank engine version of his "Precursor" Class.

[3] Chronologically, the class was constructed three distinct blocks, from May to September 1906 (works nos.

Due to their weight, the Precursor Tanks were unable to operate on some branch lines, but had primarily been designed for use on heavy suburban trains.

[4][5] Initially, they were put to work on local services between Sutton Coldfield and Birmingham, and also between Watford and London Euston.

[5] 1572, which was possibly one of the earliest locomotives to have the initials "L&NWR" on its sides replaced by "LMS", was noted to be working on the Morecambe branch in 1923.