The success of the Liverpool & Manchester set off three decades of explosive expansion. Britain went railway-mad — building the trunk routes that still carry the nation, fighting over the very width of the track, and learning hard lessons about financial speculation.
The trunk routes
Through the 1830s the great main lines drove out from London: Robert Stephenson's London & Birmingham, the Grand Junction, and the line from London to Bristol built by the Great Western's engineer Isambard Kingdom Brunel. These were engineering epics, demanding vast cuttings, embankments, tunnels and viaducts dug by armies of navvies.
Railway Mania
The 1840s brought “Railway Mania” — a speculative frenzy in which hundreds of companies were promoted and thousands of miles of line authorised in a few years. The financier George Hudson, the “Railway King”, rose to enormous power before crashing in scandal. When the bubble burst many schemes collapsed — but a huge proportion of Britain's railway map was fixed in this single decade.
The gauge wars
The era's great technical quarrel was over gauge. Most companies followed Stephenson's standard gauge of 4 ft 8½ in, but the Great Western adopted Brunel's broad 7 ft gauge for its speed and stability, running superb engines such as the Iron Duke class designed by Daniel Gooch. The two systems could not interwork; after a Royal Commission, the Gauge Act of 1846 settled Britain's future in favour of standard gauge, though the GWR clung to broad gauge until a single extraordinary conversion weekend in 1892.