Ditherington Flax Mill in Shrewsbury was the first iron-framed building in the world in 1797. Thomas Bolton & Sons of Froghall, Staffordshire, made the world's first transatlantic telegraph cable in 1857, having supplied a submarine cable across the English Channel in 1850. GEC Telecommunications was headquartered at the GEC Telephone and Radio Works in Coventry, it has now become the New Century Park, off the A428 north of Stoke Aldermoor in eastern Coventry. On 10 July 1890, a trunk circuit telephone line was opened between London and Birmingham by the National Telephone Company; for the first time this allowed phone calls between the London and the north. The world's first coaxial cable was laid between London and Birmingham in 1936 to give 40 channels for telephone traffic. and brought into use in 1938, later extended to Manchester in 1940.