Motion sickness was common among passengers on early railways, It was caused by a combination of speed and the jolting of the primitive carriages.
Motion sickness was common among passengers on early railways, It was caused by a combination of speed and the jolting of the primitive carriages.

Opening of the Glasgow, Paisley, Kilmarnock & Ayr Railway, 11 August 1840
The line opened in stages. The section from Ayr to Irvine opened on 5 August 1839. The extension to Kilwinning opened on 23 March 1840 and to Beith on 21 July 1840. The completed line between Ayr and Glasgow opened on 11th August 1840.
Reference: http://en.wikipedia.org/wiki/Glasgow,_Paisley,_Kilmarnock_and_Ayr_Railway (accessed 08Feb21)
The Caledonian Mercury, 13th August 1840 reports that the train comprised "Eleven first class carriages, each seated for eighteen persons, and ten second class, each seated for twenty- four," This agrees with the 21 carriages claimed by the song and also the estimate of 400 passengers.
It was common for railway companies to provide special costumes for the navvies to wear at opening ceremonies