Manufactured by Marshall & Sons & Co. Ltd at Britannia Works in Gainsborough, Lincolnshire UK from 1930 to 1957

Marshall's were a prominent boiler maker in this country and were producing a large number of steam ploughing engines up to the 1920's. They started to produce tractors based on the Lanz tractors

Marshall introduced it's first machine In 1930 which was the 15/30 tractor. It had a single cylinder engine of 8" bore by 10.5" stroke, which ran at 550 rpm, with a compression ratio of 15:5/8:1, and was started using ignition papers in a holder which protruded from the combustion chamber.Three forward and one reverse gears were used.

In 1933 a revised model known as the 18/30 was introduced. There were changes in appearance and some reductions in weight, but also some strengthening of the rear transmission housings and a Bosch unit and injector used to get over fuel problems.

In 1934 the 12/20 was introduced with an engine that was now 6.625" bore by 9"stroke. Pneumatic tires became available. This was a popular and reliable design that would continue unchanged through the years to come.

The 12/20 was renamed the "M" after 4 years with refinements to the gearbox and engine castings, and an increase in engine revs to 700rpm.

In 1945 the Field Marshall name was adopted for range of wheeled tractors and the Field Marshall Series 1 was launched. It was a more modern looking machine with cosmetic changes to hide working parts with sheet metal.

The engine was essentially the same but speed had been increased from 700 to 750 rpm. Modifications were also made to the cylinder head to allow for power starting. There was provision for power steering, along with improvements to the clutch and strengthening of the transmission.