 In the meantime Maunsell settled upon producing a 3-cylinder version of the N class 2-6-0, which provided the opportunity to test a variant of the Gresley conjugated valve gear developed by his assistant, Harold Holcroft.Maunsell and Holcroft completed plans for a new 3-cylinder locomotive in 1919.Designated N1, the new design was an attempt to increase the operational flexibility and power of the SECR 2-6-0 without substantially increasing axle loading.