Nice try at an urban legend, Bill. Were they singing 'Ring Around the Rosie'? Haha.

From Wikipedia:
Blackstone cites the first recorded usage of habeas corpus ad subjiciendum in 1305, during the reign of King Edward I. However, other writs were issued with the same effect as early as the reign of Henry II in the 12th century. Blackstone explained the basis of the writ, saying:
"The King is at all times entitled to have an account, why the liberty of any of his subjects is restrained, wherever that restraint may be inflicted."