The continuing need to grasp the nettle in terms of Drummond's first two 4-6-0 classes meant that he went back to the drawing board to create another design.

The LSWR's immediate traffic needs were covered by the relatively successful G14 design of 1908, though with only five locomotives in the class, they were unable to undertake the haulage of all heavy boat train services.

[1][page needed] The design's proven ability to pull trains at faster speeds and their larger power-to-weight ratio on other lines led Drummond to continue developing the concept.

However 0449 (renumbered to make way for the new N15) ran for several months, as part of the development work for the Lord Nelsons, at the same time of its alleged rebuild as the new N15 449 was running in.

[1][page needed] The P14s continued in their Drummond guise without modification until they were rebuilt in 1925 by Richard Maunsell, who used the parts to create a new batch of N15 locomotives.