On 25th May 1999, the last pit pony in the South Wales coalfield, 'Robbie' worked his last day underground at Pant y Gasseg, Pontypool.
At its peak in 1913, there were 70,000 ponies working underground in Britain's coal mines.... In later years, mechanical haulage was quickly introduced on the main underground roads replacing the pony hauls, and ponies tended to be confined to the shorter runs from coal face to main road . As of 1984, 55 ponies were still in use with the National Coal Board in Britain.
Larger horses, such as varieties of Cleveland Bay could be used on higher underground roadways, but on many duties small ponies no more than 12 hands high were needed. Shetlands were a breed commonly used because of their small size. In shaft mines, ponies were normally stabled underground and fed on a diet with a high proportion of chopped hay and maize, coming to the surface only during the colliery's annual holiday. In slope and drift mines, the stables were usually on the surface near the mine entrance. Typically, they would work an eight-hour shift each day, during which they might haul 30 tons of coal in tubs on the underground narrow gauge railway. One 1911 writer estimated that the average working life of coal mining mules was only 3 1/2 years, where 20-year working lives were common on the surface. See More