Legal & General (L&G) has ploughed £350m into the UK’s train network as the Government seeks to meet a promise to upgrade Britain’s aging stock.

L&G is helping to finance a fleet of 665 Bombardier Aventra trains that will be leased to Abellio East Anglia from next year.

The £183m investment was made on behalf of the pension fund’s retirement division, and is part of a total of £835m made by different investors to fund the fleet for a train leasing company called Angel Trains.

Angel Trains will then lease the trains to Abellio, the private company that runs the route.

Separately, L&G has also provided cash to supply 400 vehicles to the UK’s West Midlands train franchise. The new trains will be manufactured by Bombardier and Spanish firm CAF, and will increase the size of the West Midlands fleet by around 25pc.

Hayley Rees, head of direct investments at L&G Retirement, said: “By helping to finance significant improvements to Britain's rail network, we can use UK pension money to help to increase capacity, relieve congestion and provide better passenger facilities, while matching our long-term income liabilities.”

The news came as commuters returning to work after the Christmas break faced fare rises of 3.4pc, the highest in five years, despite Britain’s trains being the oldest since records began.