Built from 1946 to 1948, the K1 used a wheelbase and was powered by a tuned version of the V8, with 7:1 compression, producing . The frame was made up from stamped steel channel sections by Thomsons of Wolverton specially for Allard. Side rails and cross members were designed to fit the Allard trailing link, transverse leaf independent front suspension and live rear axle. Production totaled 151 and fitted with the same engine options as the J1 the K1 could reach .