With a railway now running near the boundary of the Wotton House estate at Quainton Road, the 3rd Duke decided to open a small-scale agricultural railway to connect the estate to the railway. The line was intended purely for the transport of construction materials and agricultural produce, and not passengers. The line was to run roughly south-west from Quainton Road to a
new railway station near Wotton Underwood. Just west of the station at Wotton the line split: one section would run west to
Wood Siding near Brill; a short stub called Church Siding would run north-west into the village of Wotton Underwood itself, terminating near the parish church, and a one mile 57 chain (one mile 1,254 yards; 2.8km) siding would run north to a coal siding near
Kingswood. He extended it soon afterwards to provide a passenger service to the town of
Brill, and the tramway was converted to locomotive operation, known as the
Brill Tramway. All goods to and from the Brill Tramway passed through Quainton Road, making it relatively heavily used despite its geographical isolation, and traffic increased further when construction began on
Ferdinand de Rothschild's mansion of
Waddesdon Manor. The plan of extending the Brill Tramway to Oxford, which would have made Quainton Road a major
junction station, was abandoned. Instead, the Aylesbury and Buckingham Railway and the Brill Tramway were absorbed by London's
Metropolitan Railway (MR), which already operated the line from Aylesbury to London. The MR rebuilt Quainton Road and re-sited it to a more convenient location, allowing through running between the Brill Tramway and the Aylesbury and Buckingham Railway. When the
Great Central Railway (GCR) from the north of England opened, Quainton Road became a significant junction at which trains from four directions met, and by far the busiest of the MR's rural stations. Construction began on the line on 8 September 1870. It was built as cheaply as possible, using the cheapest available materials and winding around hills wherever feasible to avoid expensive earthworks. The station platforms were crude earth banks high, held in place by wooden planks. As the Duke intended that the line be worked by
horses, it was built with
longitudinal sleepers to reduce the risk of them tripping. On 1 April 1871, the section between Quainton Road and Wotton was formally opened by the Duke in a brief ceremony. At the time of its opening, the line was unnamed, although it was referred to as "The Quainton Tramway" in internal correspondence.{{#tag:ref|When built, the Duke of Buckingham's tramway had no official name; it was referred to in internal correspondence as "The Quainton Tramway".{{sfn|Melton|1984|p=16} Following the 1872 extension and conversion to passenger use, it was officially named the "Wotton Tramway". On 1 April 1894, the Wotton Tramway was taken over by the Oxford & Aylesbury Tramroad, and retained the O&AT name officially until closure in 1935 despite never running either to Oxford or to Aylesbury. It was commonly known as the Brill Tramway from 1872 onwards (and referred to as such in some official documents such as the agreement establishing the
Metropolitan and Great Central Joint Committee), and as the Metropolitan Railway Brill Branch from 1899 to 1935, but neither of these were official names.|group=note}} The extension from Wotton to Wood Siding was complete by 17 June 1871; the opening date of the northern branch to Kingswood is not recorded, but it was not yet fully open in February 1873. The London and North Western Railway immediately began to operate a dedicated service from Quainton Road, with three vans per week of milk collected from the Wotton estate shipped to
Broad Street. Passengers were not carried, other than estate employees and people accompanying livestock. The tramway did not link to the A&B, but had its own station at Quainton Road at a right angle to the A&B. A diameter
turntable at the end of the tramway linked to a spur from the A&B. This spur ran behind a goods shed, joining the A&B line to the northwest of the road. The Tramway had no buildings at Quainton Road, using the A&B's facilities when necessary. As the tramway ran on the east side of the road, opposite the station, the spur line had its own level crossing to reach the main line. In 1871, permission was granted to build a direct connection between the two lines, but it was not built.
Expansion of the Wotton Tramway In late 1871, the residents of
Brill, the former seat of the
Mercian kings and the only significant town near Wotton House, petitioned the Duke to extend the route to Brill and to run a passenger service on the line. In January 1872, a passenger timetable was published for the first time, and the line was officially named the "Wotton Tramway", but it was commonly known as the "Brill Tramway" from its opening to passengers until closure. The new terminus of
Brill opened in March 1872. With horses unable to cope with the loads being carried, the Tramway was upgraded for
locomotive use. The lightly laid track with longitudinal sleepers limited the locomotive weight to a maximum of nine tons, lighter than almost all locomotives then available, so it was not possible to use standard locomotives. Two
traction engines converted for railway use were bought from
Aveling and Porter at a cost of £398 (about £ as of ) each. The locomotives were chosen on grounds of weight and reliability, and had a top speed on the level of only , taking 95–98 minutes to travel the six miles (10 km) between Brill and Quainton Road, an average speed of . The line was used heavily for the shipment of bricks from the brickworks around Brill, and of cattle and milk from the dairy farms on the Wotton estate. By 1875, the line was carrying around 40,000 gallons (180,000 litres) of milk each year. Delivery of
linseed cake to the dairy farms and of coal to the area's buildings were also important uses of the line. The line also began to carry large quantities of manure from London to the area's farms, carrying 3,200 tons (3,300 tonnes) in 1872. As it was the only physical link between the Tramway and the national railway network, almost all of this traffic passed through Quainton Road station. By the mid-1870s, the slow speed of the Aveling and Porter locomotives and their unreliability and inability to handle heavy loads were recognised as major problems for the Tramway. In 1874,
Ferdinand de Rothschild bought a site near the Tramway's
Waddesdon station to use as a site for his country mansion of
Waddesdon Manor. The Tramway's management recognised that the construction works would lead to a significant increase in the haulage of heavy goods, and that the Aveling and Porter engines would be unable to cope with the increased loads. The newly established engineering firm of
W. G. Bagnall wrote to the Duke offering to hire a locomotive to him for trials. The offer was accepted, and on 18 December 1876, the locomotive was delivered. The tests were generally successful and an order was placed to buy a locomotive from Bagnall for £640 (about £ in ) which was delivered on 28 December 1877. With trains now hauled by the Bagnall locomotive (the Kingswood branch generally remained worked by horses, and occasionally by the Aveling and Porter engines), traffic levels soon rose. Milk traffic rose from 40,000 gallons carried in 1875 to 58,000 gallons (260,000 L; 70,000 US gal) in 1879, and in 1877, the Tramway carried a total of 20,994
tons (21,331 t) of goods. In early 1877, the Tramway was shown on
Bradshaw maps for the first time, and from May 1882
Bradshaw included its timetable. Although the introduction of the Bagnall locomotives and the traffic generated by the works at Waddesdon Manor had boosted the line's fortunes, it remained in serious financial difficulty. The only connection with the national railway network was by the turntable at Quainton Road. Although the 3rd Duke of Buckingham was both the owner of the Wotton Tramway and Chairman of the A&B, the latter regarded the Tramway as a nuisance, and in the 1870s, pursued a policy of charging disproportionately high fees for through traffic between the Tramway and the main line, with the intention of forcing the Tramway out of business. A&B trains would deliberately miss connections with the Tramway, causing milk shipped via Quainton Road to become unsellable. The Tramway sought legal advice and was informed that the Duke would be likely to win a legal action against the A&B. However, the A&B was in such a precarious financial position that any successful legal action against it would likely have forced its through Quainton Road to close, severing the Tramway's connection with the national network. Many Tramway passengers changed trains at Quainton Road to continue their journey on the A&B; in 1885, 5,192 passengers did so. The Tramway's management suggested that the A&B subsidise the Tramway to the sum of £25 (about £ in ) per month to allow passenger services to continue, but the A&B agreed to pay only £5 (about £ in ) per month. By the mid-1880s, the Tramway was finding it difficult to cover the operating expenses of either goods or passenger operations. ==Metropolitan Railway takeover of the Aylesbury and Buckingham Railway==