The explosion in railway construction had tended to conform to the standard gauge of four feet, eight and one half inches, but Brunel opted for his "broad gauge" of seven feet and one half inch. This, he reckoned, meant not only hitherto unknown standards of passenger comfort, but also consumed less fuel.

The first part of the line opened to passengers in 1838 between London and Maidenhead, with the remaining sections opened for use in 1841. There were some very serious natural obstacles to overcome once the line was clear of Reading, with the relief of the landscape being more undulating than that of the home counties. The biggest challenge of all was Box Hill, too high to climb over and too wide to go round -- so Brunel went through instead, and excavated what was then the longest rail tunnel in the world, at slightly over three kilometres (two miles). Such was the scale of the challenge, and such was the hardness of the rock, that Brunel reputedly used a ton of gunpowder per day for the blasting operation.

The tunnel took over two years to construct, but once finished, the line was complete. To celebrate such a feat, Brunel oversaw the construction of two great terminals at either end of the line: one at Paddington, the other at Bristol Temple Meads. The Bristol station occupied a site slightly removed from the current station, as in those days, it was "the end of the line". Modern Temple Meads now carries passengers not just to London, but to the Midlands, South Wales, and the South Coast.

The old broad gauge station still sits alongside the new and features an ornate interior and high, vaulted glass roof, which was to become standard design for all of Brunel's creations. Unfortunately, although a grade-one-listed building, it is being used predominantly as a car park, which doesn't really give the place a proper ambience, but to see the wide spaces where once were platforms and the magnificent facades, you can almost imagine the Victorian businessmen scurrying to catch the train.