Not sure who wrote the proper words (as opposed to the risque words as in "brothers Morgan, Matthew etc) but one source gives the tune as being from an old Welsh folk tune "The Black Pig". Cosher was a real person, an ironmaster who built (or had built) the Taff Vale Railway in 1846. According to local legend Cosher drove the first train and got the loco stuck in a tunnel. The Taff Vale, was at one time the most profitable railway in the U.K, (at a time when Britain was at war and good steam coal required to fuel the navy's ships was at a premium). Cosher died in 1872. His railway was at the centre of the infamous row in the early 1900's that led the Amalgamated Society of Railway Servants to be central to the formation of the committee for Labour Representation (Labour Party) to seek immunity from punitive punishments dished out when the Taff Vale Company took them to court during a most acrimonious dispute. One of the Taff Vale locomotives now over 100 years old is currently pulling trains on the Worth Valley Railway in West Yorkshire. This is not the loco that got stuck, it was built by Dubbs & Co in Glasgow in 1898?