A computer enhanced image of how the Tornado will look

The Darlington-based A1 Steam Locomotive Trust has already raised the majority of the �2.5m needed to see the locomotive finished by the end of 2007.

The trust was formed in 1990 by a group of steam train enthusiasts.

In a milestone event later this month, the boiler for the A1 peppercorn class engine will be delivered to the trust.

When completed the locomotive - dubbed Tornado - will be used for charter journeys operated by Network Rail.

Major hurdle

The boiler was manufactured by a company in Germany and will be installed using a 20-ton crane.

Mark Allatt, chairman of The A1 Steam Locomotive Trust, said: "The completion of the boiler is tremendous news for Tornado and the future of mainline steam in Britain.

"The boiler is the single most expensive component and its delivery marks the overcoming of the last major engineering hurdle in the construction programme.

"When this project was launched in 1990 many people said that it could not be done. "The delivery of the boiler proves the doubters wrong and means that there is only �195,000 and 100 weeks between now and Tornado's mainline debut."

The A1 class of Pacific locomotives was designed by Arthur H Peppercorn for the London and North Eastern Railway and built in 1948/49.

They were the last of the East Coast Main Line's series of express passenger steam locomotives.