The company was started in 1836 at McAlpine Street by Walter Neilson and James Mitchell to manufacture marine and stationary engines.

Through the 1870s considerable numbers of 0-4-4 tank engines were built for the London, Chatham and Dover Railway, the Midland and the Great Eastern.

Many other types were built for railways at home and abroad, including fifty 0-4-2s for India.

In 1879 the first 2-6-0s to run on British rails were built for William Adams of the Great Eastern.

The Engineer journal in 1883 carried a photograph of a Neilson 4-6-0 with Joy valve gear produced for the Cape Government Railways.

However, by this time, intense competition from United States meant that small companies were unable to survive.

0-6-0+4 “Itatí” Preserved at Liniers Club APDFA, Ciudad Autónoma de Buenos Aires.

0-6-0+4 “Monte Caseros” Preserved on work at Ferroclub Argentino, province of Buenos Aires.

In 1876, the company founded an association football club, called the Hyde Park Locomotive Works, playing in red and white 2 inch hoops.