Fire Fly 2-2-2 locomotive 1840
A history of the broad gauge needs to be put in perspective with the social and economic history of the times. The early 19th century saw a rapid growth in industrialisation, with Britain moving from a predominantly rural economy to an industrial nation. This brought about a rapid move in population from the countryside to the new cities, and caused much social upheaval. On continental Europe this upheaval fuelled periodic revolutions and wars. The constant fear of organised social unrest was a factor behind the initial reluctance to convey "lower classes" on trains.
The success of the Liverpool and Manchester Railway, opened in 1830, prompted a huge number of other railways to be promoted. The period between the mid 1830s and 1845 was known as the Railway Mania as investors sought quick profits by investing in railway shares. Even the most unlikely schemes attracted investors. This abruptly came to an end in the summer of 1845 when many of the railways approved by parliament in the early 1840s started to ask their shareholders for the money due on their shares. This caused railway shares to plummet in value and several railways to go bankrupt. For a modern day equivalent of this effect, recall how technology and internet shares boomed in the late 1990s and collapsed in 2001.
This boom and bust period had a profound effect on the history of the Great Western Railway and the broad gauge in general. The initial line between London and Bristol was very profitable, and the GWR paid a dividend of 8% in 1845. In the early 1840s, the GWR shareholders encouraged the company to expand into other regions and the company made large investments in several other proposed connecting railways, subject to them being built to the broad gauge. The financial troubles in the late 1840s saw many of the schemes backed by the GWR run into difficulty and require substantial extra financial support from the GWR. This in turn caused the GWR to have difficulty in raising capital, and it had to borrow money at high interest rates. These financial constraints continued through the 1850s, with the GWR dividend reducing to only 1¼% in 1858.
Changing alliances between railways also affected the GWR. An amalgamation between the GWR and the Bristol & Gloucester Railway failed at the last minute when the Midland Railway made a better offer. The line to Birmingham, in competition with the well established London & Birmingham Railway, was supported by the GWR in anticipation of traffic from the Grand Junction Railway (which connected Liverpool and Manchester to Birmingham). However, by 1848, the Grand Junction Railway had settled its differences with the London & Birmingham Railway and had in fact merged with it to form the London & North Western Railway (LNWR). The GWR supported line was therefore destined to always be a secondary route between Birmingham and London.
The early 1860s saw a further period of expansion, when the GWR acquired several standard gauge railways, frequently paying a premium to defeat competitor railways (often the LNWR) from acquiring them. Many acquired railways were formally merged into the GWR by the Amalgamation Acts of 1863. These amalgamations meant the GWR had almost as much standard gauge as broad gauge track, and the end of the broad gauge was contemplated. A banking crisis in 1866 caused a period of financial difficulty for a few years and delayed plans to convert several broad gauge lines to mixed or standard gauge.
By the mid 1870s the GWR had converted all its broad gauge lines and only retained the mixed gauge main line from London to Bristol for through traffic to the Bristol & Exeter Railway and beyond. In 1875, the Bristol & Exeter Railway and South Devon Railway agreed to amalgamation terms with the GWR. These amalgamations took effect in January and February 1876 respectively, and with it the GWR also acquired sole operating rights over the Cornwall Railway and West Cornwall Railway. The two Cornwall railways had never recovered from the financial difficulties of the 1840s, and while technically they remained independent companies, had been totally reliant on financial support from their eastern neighbours ever since.
After acquiring the Bristol & Exeter Railway and South Devon Railway, the GWR converted a number of lines in north Devon and Somerset to standard gauge. In 1885, the directors of the Cornwall Railway requested the GWR to arrange conversion of its line to standard gauge at an opportune time. As a consequence of this request, plans were made to bring the broad gauge to an end in May 1892.
In retrospect, the broad gauge only delivered Brunel's vision of a high speed railway for a short period in the late 1840s. Broad gauge express locomotive design never developed much beyond Gooch's "Iron Duke" class of 1848, while standard gauge locomotive design advanced considerably during the latter half of the 19th century. After the early 1860s no attempt seems to have been made to operate broad gauge trains faster than standard gauge trains, although the wider gauge would have enabled it.