What were "chainboys and slipper lads"?

[S&CLER]

A census of railway employees for March 1923 classifies them by grade. With one exception it's obvious what these grades did, but I'm baffled by the grade "chainboys and slipper lads". Can anyone help? Whatever they did, there were only 25 of them in 1923. Google gives another reference from 1904, but it only adds the term "chockers" to this grade.

 

[furnessvale]

We had "chainmen" in the engineers dept to assist surveyors but probably not related.

 

[John Webb]

Were they young lads who accompanied horse-drawn carts etc.? On ascending a steep hill they might walk just behind a rear wheel to insert a chock behind the wheel if the horse(s) needed a rest. On descents it was common to put a chock, held to the cart by a chain, under a rear wheel; this then acted as a brake to prevent the cart going too fast.

It's also possible that a surveyor might use a boy to carry his 'chain' used in surveying, although it seems unlikely they would have been included in the same category as the other occupations - whatever they might be!

 

[randyrippley]

DOOT: 704.—Shunters, Pointsmen, and Level Crossing Men

Digital edition of A Dictionary of Occupational Terms Based on the Classification of Occupations used in the Census of Population, 1921.

doot.spub.co.uk

chain horse driver see shunt horse driver.
chain horse lad ; slipper boy or lad assists shunt horse driver q.v.; attaches and detaches (slips) chain hook from truck to slacken speed, etc.; holds horse when not working.

shunt horse driver ; chain horse driver, horseman (shunting), horse pilotman, horse shunter, pilot shunter, truck horse driver is in charge of horse which draws trucks or coaches into or out of railway sidings or on to branch line during shunting operations; yokes and unyokes horse to and from truck or coach, as necessary; grooms and attends to horse where there is no stableman (725) q.v.