LONDON—A “potentially dangerous situation” was defused by London police Monday morning, as a toddler cutting Play-Doh with a toy plastic pocketknife was tackled to the ground and apprehended by a Specialist Firearms Command unit, sources confirmed at the scene. The toddler was happily cutting a lump of green-ish Play-Doh with his official Play-Doh pocketknife in his mum’s London flat when a Metro Police unit kicked his door down and charged in, bellowing for everyone to get down on the ground. Several other operatives dove through windows and rappelled from skylights, tossing tear gas and breaching doors throughout the home...