... The extra .5" on the track gauge has puzzled people for some time. Why not 4ft 8"? It fact the first railways in the UK were built to 4ft 8". The answer may come from recent research into the Stockton and Darlington Railway. This line was Built by George Stephenson and opened in 1825. He followed the same pattern as his earlier railways in Northumberland and Durham and made the gauge 4ft 8" and the first locomotives, being 0-4-0 were relatively short wheel base (about 4ft) and therefore had no trouble in negotiating the curves on the line. The engineer in charge of the S&DR, Timothy Hackworth soon found that these primitive locomotives were underpowered and costly and so, following a visit by some Prussian engineers in 1827, decided to build his own locomotives. To increase power he designed an 0-6-0 with a rigid wheelbase of 8ft 7", over twice the average of the original fleet. Locomotive #5 Royal George entered service late in 1827 but soon was found to derail and attempt to straighten the curves. The locomotive was sketched by John U Rastrick in 1829 on his visit in June of that year. Undaunted Hackworth set about widening the gauge by .5" to permit the longer wheelbase. This had no affect on the existing fleet as the width of the tyres was enough to accommodate the gauge widening. Gauge widening was easy because the rails were held in stone blocks and it was simply a matter of edging one line of blocks outwards and repacking. Hackworth told Stephenson what he had done and the locomotives continued to be built to 4ft 8" but from then on George Stephenson and his son Robert built track to 4ft 8.5" and so the "standard" gauge was born.