In Britain and Ireland, a large number of enterprising early birds made a living waking people for work.A commenter notes this passage in Sybil or The Two Nations by Benjamin Disraeli
A knocker-up would be paid a few pence a week to make the rounds and rouse workers, banging on their doors with a short stick or rapping on upper windows with a long pole. The knocker-up would not move on until he received confirmation that his drowsy client was up and moving.
The profession died out in the 1920s as alarm clocks became cheaper and more reliable, but a few specialized knockers-up — such as Doris Weigand, employed by a railway depot to summon workers for short-notice shifts — survived for a few decades more.
A man muffled up in a thick coat, and bearing in his hand what would seem at the first glance to be a shepherd’s crook, only its handle is much longer, appears upon the pavement. He touches a number of windows with great quickness as he moves rapidly along. A rattling noise sounds upon each pane. The use of the long handle of his instrument becomes apparent as he proceeds, enabling him as it does to reach the upper windows of the dwellings whose inmates he has to rouse. Those inmates are the factory girls, who subscribe in districts to engage these heralds of the dawn; and by a strict observance of whose citation they can alone escape the dreaded fine that awaits those who have not arrived at the door of the factory before the bell ceases to sound.