Train builders will on Wednesday be invited to bid for the UK’s largest train order since privatisation over a decade ago when the Department for Transport issues a tender for hundreds of new carriages for the vital cross-London Thameslink route.

The new trains, expected to cost around £1.4bn ($2.8bn), will substantially increase passenger capacity on the route, which is to undergo a £3.5bn upgrade that will increase the number of trains and open up more northern destinations.