The government of Sir George Grey had approved the construction of the line, which was included in the Public Works Estimates of 27 August 1878.

[2] In May 1881 the company signed a contract with the government to purchase the land, formation and materials used for building the line so far (which had already cost £30,000).

[6] The contract also included a clause for the government to purchase the company in the future at a "fair value", something that was later to prove contentious.

[8] Construction was completed on 27 October 1886, with the first through train running on 3 November;[2] see Wellington–Manawatu Line The WMR was relatively successful and generated considerable revenue.

So the government offered in settlement with WMR only £5,339 worth of land in 1894, knowing the company could not afford a lawsuit.

The company had paid the government and local bodies £118,550, amounting to two-thirds of its paid-up capital and 20% more than the total value of the land grants.

[9] The railway's operations were advanced by standards of the time, having comfortable carriages, dining cars, electric lighting, and telephone communication between stations.

[12] The WMR was bought by the government in 1908 (as soon as it could be purchased without penalty), and was integrated into the New Zealand Railways Department from Monday 7 December 1908.

The NZR also took over 20 locomotives, 56 bogie passenger cars, 14 brake vans, 343 wagons and two 10-ton hand cranes.

[15] From Tawa to Longburn the North Island Main Trunk line generally follows its route, through Porirua, Paekākāriki, Paraparaumu, Otaki, and Shannon.

A number of new towns were established along the route, notably Plimmerton, named after company director and "Father of Wellington" John Plimmer.

WMR passenger trains eventually ran to Palmerston North Central railway station.

10 became particularly famous when, on 20 July 1892, it achieved 64.4 mph (103.6 km/h) hauling a test train along the level stretch of line between Levin and Shannon, at the time the world speed record for the 1,067 mm (3 ft 6 in) gauge.

The locomotive was withdrawn in 1928 and dumped in the Waimakariri River to help stabilise the riverbank, and its final resting place is a mystery.

3 or Jumbo (WJ class) banked north out of Wellington for 25 years (to 1927) on the long and steep 1 in 40 grades up to Crofton (Ngaio) and Khandallah.

Despite the WMR's short history and its disappearance long before the railway preservation movement began, a number of relics have survived.

A number of items of rolling stock survive, including three passenger carriages – 50 ft cars No.

The bell at the concourse end of Wellington railway station's platform 6 is believed to be from either WMR locomotive no.

Infrastructure remains include the Johnsonville Line, a stone plaque on the eastern abutment of the bridge across Hutt Rd in Wellington, the foundations of the Belmont Viaduct near Johnsonville, most of the NIMT north of Tawa, the railway station at Shannon, the former Te Horo station (now at the Tokomaru Steam Museum) and the Forest Lakes rail bridge.