Obviously WWI not earlier, as the Boy Scouts only started in 1907.

The "taking of the Queen's shilling" was presumed when the Navy "Press-ganged" men from the pubs of an earlier time. Recruitment officers would provide a round of drinks for men who appeared well intoxicated, and a shilling would be found in the bottom of the tankard, hence showing that the men had "Accepted the shilling". The men would wake up the next day already at sea.

Nigel