Helmdon Viaduct was a creation of Walter Scott & Co. and formed part of the Great Central Railway's construction contract no.5, covering the section from Woodford to Brackley. Opened to goods traffic in July1898, and on 15 March 1899 to passenger traffic, this nine-arch, brick structure on 'the last main line' sits just west of the village which give it its name. Trains on the route came to a grinding halt in September 1966. During its construction and that of the railway line, a large camp to house the navies was built nearby.
 

"The Helmdon valley is crossed by two banks and a viaduct of nine arches, each of 34ft 3in span and of the same general design as those at Catesby and Brackley. The treacherous nature of the clay foundations necessitated the distance between the piers being bricked in with five rings of brindle brickwork in cement".

From Fielden's Magazine, Vol. 2, 1900.

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