During the summer of 1956 the Banbury to Buckingham section of the Banbury to Verney Junction branch line was chosen as the location for a single railcar experiment to encourage greater passenger patronage on the branch which was suffering from low receipts in the face of competition from buses and motor cars.

The units would run from Banbury to Buckingham where a connection would be made with the traditional steam push-pull service to Bletchley.

[1] New halts were opened at Radclive and Water Stratford and a third was proposed on the edge of Buckingham but not provided.

They were equipped with little other than a simple wooden painted nameboard and several old LNWR oil lamps; there was no shelter for passengers nor even a bench.

M79900 and M79901, resulted in a reported 400% increase in traffic and were well used especially on market days and Saturdays when both ran together, carrying up to 120 passengers.