The director of engineering touches the computer screen and calls up the unmistakable form of a P2 engine, one of the largest and most powerful steam engines ever built in Britain. He moves his finger to rotate the image and zooms in on the driving crank axle. Immediately the computer brings up the detail, showing the groove cut into it.
“This is where Nigel Gresley always had trouble,” David Elliott says. “The computer can now tell us why, if we reproduce the stresses in the axle”. Cracking appears, radiating outwards from the sharp corner of the groove. “We can improve on the 1934 design if we round off the corners and machine a stress-relief groove to prevent the stresses spreading”.
The computer rests on a table. Beside it, looming up high and magnificent in the historic steam engine workshop in Darlington, cradle of Britain’s railways, stands the bulky frame of the engine. Even half-built, resting on its wheels and with the driver’s cab already in position, it is an imposing monster.
Today’s computers can explain things that even the best mechanical engineers of the old London and North Eastern railway (LNER) were unable to fathom. Computer models can demonstrate why, for example, the P2’s poppet valve gear wore too quickly: the principles were fine but the stresses were too great for the metallurgy of those days. Steel is tougher today. And computer-assisted design can analyse, improve and innovate. Elliott can not only reproduce the brilliant engineering of the LNER in its heyday; he and the trust building The Prince of Wales, a successor to Gresley’s famous Cock o’ the North, will be able to come up with an improved locomotive, fit to haul enthusiasts at high speed from one end of Britain to the other.
Do purists allow heritage to be improved by modern technology? It certainly makes some projects cheaper and feasible. A century ago, draughtsmen had to produce sheet after sheet of detailed drawings to show the founders, metallurgists and engineers how a locomotive’s innards would fit together. Now the computer can simply be hooked up to a cutter that will follow the exact detail of what it is told. A new steam locomotive can be built with only a handful of designers and craftsmen, buying in specially commissioned components from all over the world.
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This does not make it quick or cheap to build a locomotive from scratch. The P2 will take another five years to complete, at a cost of about £5 million. However, since the project was launched hard on the heels of Tornado, Britain’s first new steam engine for 50 years, the money has poured in. Thanks partly to a growing wave of nostalgia for Britain’s steam heritage and partly to the shrewd marketing tactics of Mark Allatt, chairman of the trust, the project has got off to a flying start. A Founders’ Club targeting 100 people, each giving £1,000, has raised more than £450,000, enough to begin construction in the 1850s carriage shed, a building dating back to the earliest days of the Stockton & Darlington railway.
The side frames are in position, the 20 huge wheels for the engine and tender have been cast and delivered, the cab is attached and the engine is beginning to take shape. Components have come from across the country: the wheels were cast in Sheffield; some 1,065 driven and fitted bolts have been delivered by Hawk Fasteners at Middlesbrough; other engineering companies are using the unusual orders as a challenge to train young apprentices.
The trust now needs to raise £700,000 a year — a tall order, but monthly covenants (a P2 for the price of a pint of beer a week) and component sponsorships to the tune of £160,000 so far, have helped. Britain is also blessed with what Allatt calls “railway bachelors” — men who never had families and whose obsession was steam railways that have bequeathed their wealth to heritage projects. Their boiler alone will cost £600,000 and will probably have to come from Germany, where Tornado was manufactured.
Weighing more than 165 tonnes, the engine will be vast. The original was built to haul 600-tonne express passenger and sleeper trains over rugged terrain from Edinburgh to Aberdeen. Only six of the 2-8-2 Mikado type were constructed — each slightly different, and all experimental as Gresley tried out new improvements. When he died in office in 1941, his successor rebuilt the P2s into ungainly type A2 4-6-2 Pacifics, and in this form the engines never ran as well. All were unceremoniously scrapped by 1961 as British Railways began to run down its steam fleet.
“We’re building a new P2, allowing us to finish the job Gresley started,” Allatt said. “We’re consciously doing the development work he would have completed if war had not come.” The new engine will be retrofitted with components later developed for the Class A1 Pacifics, already incorporated in Tornado. It will also have to be redesigned to incorporate all the electronics mandatory for any locomotive permitted to run on Britain’s mainline railways.
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Britain’s love of steam shows no sign of abating. More than 230 engines, many rescued from a scrapyard in south Wales and lovingly rebuilt, are running on a myriad of preserved lines or are in various states of restoration. But with the demise of all the old workshops — in Swindon, Ashford, Eastleigh, Doncaster, Leeds, Glasgow, Darlington and elsewhere — the challenge now is to build new locomotives from scratch. Steam enthusiasts are tribal, however, and loyalties to one or other of the Big Four railways companies existing before nationalisation are intense. Both Tornado and Prince of Wales are LNER engines; across the Pennines supporters of the old London, Midland and Scottish railway are racing to complete their own £1.75 million Patriot-type locomotive, The Unknown Warrior, now being built in Llangollen.
Altogether there are more than 30 projects to build new steam engines, some based on a few rusting components saved from the scrapyard and others machined anew. Not all are commercially realistic. Costs rise, fundraising is ever tougher and Allatt estimates that the rate of progress of one lackadaisical project will not see a completion date for the next 3,000 years.
Today’s steam engines will have to adapt to far tougher conditions: a crowded national network, more stringent safety regulations, heavier loads, faster acceleration, no water towers or water troughs between the rails, and longer cycles between boiler maintenance. The P2 team thinks it can produce an engine tougher than anything Gresley devised. Thanks to Thomas the Tank Engine, preserved railways and Santa specials for the children, Britain’s new railway “heritage” has captured the enthusiasm of millions. But is it authentic?