	Also during this period Norton developed a family of three similar smaller-capacity twin cylinder machines: first the Norton Jubilee 250 and then the Navigator 350 and the Electra 400, which had an electric starter. These models were Norton's first use of unit construction. The engine was an entirely new design by Bert Hopwood and the frame and running gear were from the Francis-Barnett range, also owned by AMC. These machines had a reputation for poor reliability.