The side engined A.E.C. Q type and the experimental rear-engined vehicles constructed by the B.M.M.O. concern were examples , but the vehicles designed and built by The Northern General Transport Co. Ltd. may be said to have anticipated modern practice to perhaps a greater extent than any other design of the period.

The company generally known locally by the fleetname `Northern` were at the time operating approximately 400 vehicles with all but 13 being single deckers. This was partly due to the number of low bridges in the area but was also a preference of the management.

It was felt that there would be scope for a single deck with accommodation for considerably more passengers than the B.M.M.O 34 seater. The regulations then in force limited the overall length to 27`6" on two axles but a third axle permitted a length of 30`0" so this was decided on to provide the extra capacity required. The side engine of the tall AEC Q type was rejected because of the longitudinal seat over the engine, the requirement being for all seats to face forward.

No engine of British manufacture could be found to meet the design requirements so the American Hercules WXRT six cylinder was imported.

The original prototype vehicle was designated SE6 (side-engined six-wheeler) and entered service in 1933. This differed from later vehicles in having the entrance behind the front wheels and only a slight front overhang.

The experience with this prototype led to the construction of five vehicles which entered service in the following year. These were 604-608 and had Short Bros bodies with 44 forward facing seats and the entrance in front of the front wheels . There was no door at the front entrance but a sliding door was fitted in the front bulkhead, separating the driver and front platform from the interior.

Following the success of the earlier vehicles the SE6 was produced on a larger scale in 1934 and some were built as coaches

Production of various types continued until 1939 and a complete list is as follows;