The first Intercity Express train to be built at Hitachi’s UK plant has been unveiled.

The train is one of 122 ordered by the government in a £5.7bn deal to run on mainlines between London and the south-west and from the capital to Scotland on the east coast route.

The Japanese manufacturer’s fleet of Class 800 trains will now mostly be produced in the UK at its plant in Newton Aycliffe, County Durham, which opened last year.

The trains can reach speeds of 140mph and can operate on diesel, or electrified tracks, or both. They are due to begin operating on the Great Western mainline from summer 2017 and on the east coast mainline the following year.

Hitachi’s Intercity Express programme (IEP) contract was controversial partly because of the bi-mode design and cost, and partly because it came at the expense of existing UK-based manufacturers. The IEP train shells are still constructed in Japan, although many other components come from UK suppliers.

Hitachi and the government have promised the trains will boost capacity, reliability and comfort for passengers.

Karen Boswell, managing director of Hitachi Rail Europe, said: “Today is a celebration of the return of train manufacturing to the north-east, supporting thousands of jobs and developing a strong engineering skills base in the region.

“The company that built the world famous bullet trains is now building the next generation of UK trains, which will deliver a step-change in intercity travel, offering more capacity, greater comfort and a lower carbon footprint.”

The plant will employ 900 people by next spring, and Hitachi’s total workforce will be more than double that as it opens new maintenance facilities for its fleet. As well as having manufactured the Shinkansen, or bullet train, in Japan, the company built the trains used in the UK’s only high-speed service, HS1 in Kent.