I did a little digging around online about the accident (because I had no idea) and this is what I came back with
While attending the opening of the Liverpool and Manchester Railway, on 15 September 1830, Huskisson rode down the line in the same train as the Duke of Wellington. At Parkside railway station, near the midpoint of the line, the locomotives made a scheduled stop to take on water. Although the railway staff had advised passengers to remain on the trains while this took place, around 50 of the dignitaries on board alighted when the Duke of Wellington's special train stopped. One of those who got off was William Huskisson, former cabinet minister and Member of Parliament for Liverpool. Huskisson had been a highly influential figure in the creation of the British Empire and an architect of the doctrine of free trade, but had fallen out with Wellington in 1828 over the issue of parliamentary reform and had resigned from the cabinet. Hoping to be reconciled with Wellington, he approached the Duke's railway carriage and shook his hand. Distracted by the Duke, he did not notice an approaching locomotive on the adjacent track, Rocket. On realising it was approaching he panicked and tried to clamber into the Duke's carriage, but the door of the carriage swung open leaving him hanging directly in the path of the oncoming Rocket. He fell onto the tracks in front of the train. His leg was horrifically mangled. The wounded Huskisson was taken by a train (driven by George Stephenson himself) to Eccles. When he reached hospital he was given a massive dose of laudanum. After being told his death was imminent he made his will, and died a few hours later.
The death and funeral of William Huskisson caused the opening of the railway to be widely reported, and people around the world became aware for the first time that cheap and rapid long-distance transport was now possible. The L&M became extremely successful, and within a month of its opening plans were put forward to connect Liverpool and Manchester with the other major cities of England. Within ten years, 1,775 miles (2,857 km) of railways had been built in Britain, and within 20 years of the L&M's opening over 6,200 miles (10,000 km) were in place. The L&M remains in operation, and its opening is now considered the start of the age of mechanised transport; in the words of industrialist and former British Rail chairman Peter Parker, "the world is a branch line of the pioneering Liverpool–Manchester run".