Definition of "sandboy"

Up and down the street not a child was to be seen. A sandboy with a donkey cart was the sole human arrangement in it.

1880, George MacDonald, Sir Gibbie, Hurst and Blackett

Drink always rubbed him the right way, and he would reach his rooms as jolly as a sandboy.

1910, O Henry, “The Rubaiyat of a Scotch Highball”, in The Trimmed Lamp

Craw was happy as a sandboy, he reported: quite his former vile self, but a bit dazed to be bearded by Luke without warning.

1977, John Le Carré, The Honourable Schoolboy, Folio Society, published 2010, page 23