It was created in response to a desperate lack of adequate locomotives in service on the LSWR that could be utilised for heavy freight duties.

The locomotive had been scheduled for major modifications by Urie's predecessor Dugald Drummond in the light of poor operational performance.

[1][page needed] It was the first locomotive to be fitted with an Eastleigh superheater, but it retained its original boiler pressure of 175 lbf/in2 (1.21 MPa).

The earlier class members mounted a lower running plate that was raised above the cylinders for clearance.

[3][page needed] These locomotives also sported a single, straight splasher above the driving wheels, an embellishment that would feature on Urie's later N15 class.

[3][page needed] A total of 26 locomotives were completed in six batches, including number 335, over a period of twelve years.

The class was provided with a 5,000 gallon Drummond 'watercart' eight-wheeled tender design that enabled them to travel on the long distances of the LSWR network which never had water troughs.

With their 21 × 28 inch cylinders allied with 6 ft 0 in driving wheels and a free-steaming boiler, they proved to be very capable of handling heavy trains.

[1][page needed] The Drummond F13 rebuild were notable for having very tall cabs, requiring footplate staff shorter than 6 foot in height to stand on improvised stools to reach some controls.

[1][page needed] All members of the class had been withdrawn by 1961 as a result of the BR 1955 Modernisation Plan, and no locomotives survived into preservation.