London County Council (Woolwich Subsidences) Act 1950
WHEREAS mining operations have in times past been carried out by persons unknown in the metropolitan borough of Woolwich (hereinafter referred to as "the borough") for the purpose of winning chalk or for some other purpose and subsidences have from time to time occurred in certain lands situated within the borough and over or in the neighbourhood of cavities in the subsoil resulting from such operations:

And whereas certain structures erected upon lands in which such subsidences as aforesaid...