Steam locomotive and tender, Great Northern Railway, 4-4-2 No 251, designed by H A Ivatt, built at Doncaster in 1902, withdrawn in 1947.

This engine, designed by H A Ivatt¸ inaugurated the ‘big engine’ era on the East Coast route, and the wide firebox in British Express locomotives.

Ivatt did not take too large a step with his first ten-wheeler and in consequence the rest of the class were elongated versions of the familiar Stirling singles. Only when the crews had adjusted to the 4-4-2s did Ivatt built the large-boilered version in the shape of No. 251.

Compared with the “Henry Oakley” type, the new boiler gave a 72% increase in evaporative heating surface. Ivatt was anxious to ensure an adequate supply of steam and No. 251 was the first example of a locomotive philosophy which was to be faithfully perpetuated by Nigel Gresley in such engines as Flying Scotsman. Size apart, the main innovation in No. 251 was the wide firebox with a larger grate area. The design was immediately successful, showing economies over its rivals, and 90 more were built up until 1910.

When new, No. 251 employed saturated that steam with balanced slide valves exhausting through their backs, operated by Stephenson link motion. The final batch of ten new engines had 8-inch diameter piston valves with large exhaust clearances. They were also fitted with superheaters and eventually proved livelier than the earlier engines and considerably more economical in fuel. Accordingly, Gresley (taking over after Ivatt’s retirement) fitted superheaters to all of the original engines. No. 251 received the largest type of superheater used on the class, but this was removed when the engine was preserved.

From World War I to the late 1930s, the superheated large-boilered Atlantics performed much of their best work. They sometimes tackled very heavy trains and achieved particular fame on the various Pullman trains of the period. Perhaps the most celebrated feat occurred in 1936, when No. 4404 deputising for a Pacific, hauled an enormoud 585 ton express over the 83 miles from Grantham to York in 88 minutes, with a top speed of nearly 80mph.

No. 251 was withdrawn for preservation in 1947 but was steamed again in 1953, along with Henry Oakley, to celebrate the Doncaster Plant centenary.