The Great Northern Railway (GNR) was a British railway company incorporated in 1846 with the object of building a line from London to York. It quickly saw that seizing control of territory was key to development, and it acquired, or took leases of, many local railways, whether actually built or not. In so doing, it overextended itself financially.

Railway Mania was a stock market bubble in the rail transportation industry of the United Kingdom of Great Britain and Ireland in the 1840s. It followed a common pattern: as the price of railway shares increased, speculators invested more money, which further increased the price of railway shares, until the share price collapsed. The mania reached its zenith in 1846, when 263 Acts of Parliament for setting up new railway companies were passed, with the proposed routes totalling 9,500 miles (15,300 km). About a third of the railways authorised were never built—the companies either collapsed due to poor financial planning, were bought out by larger competitors before they could build their line, or turned out to be fraudulent enterprises to channel investors' money into other businesses.