Before the 1890s the most extra training railway clerks could undertake, above what was required for their posts, was in shorthand. On the Manchester Sheffield and & Lincolnshire Railway in 1854 the General Manager, Sir Edward Watkin, employed the brother of Isaac Pitman (the inventor of shorthand) to run classes for a small number of clerks. Thereafter, its teaching was gradually adopted by other railways companies and became a standard skill for the vast majority of railways' clerical staff by the turn of the century. Indeed, in 1910 shorthand was mandatory skill for all new junior clerks on the London and North Western Railway. Yet, even at the end of the century some companies remained behind the times. As late as 1891 the London and South Western Railway's staff magazine, The South Western Gazette, was still imploring juniors to attend classes. Indeed, to my knowledge the company never made it mandatory.
I wrote a longer history of shorthand on the railway (that may need updating with new information) on my main Turnip Rail Blog in October 2010 here.
 Hodgkins, David, The Second Railway King: The Life and Times of Sir Edward Watkin, (Landybie, 2002)
Pitman, Isaac, The Phonographic Railway Phrase Book: An adaptation of Phonography to the Requirements of Railway Business and Correspondence, (London, 1889), p.1
 Pratt, Edwin A., A History of Inland Communication and Transportation in England, (London,1912), p.42
 South Western Gazette, Nov 1891, p.3