Class War Breaks Out in London Rhubarb Patch

Guerrilla gardeners take on aristocratic family that wants to build houses where they tend vegetables

LONDON—Ralph George Algernon Percy, the 12th Duke of Northumberland, comes from a storied English aristocratic family that deposed a king, repelled invasions and raided France.

Meet the House of Percy’s latest adversary: Annie Aloysius, a London health worker who likes rhubarb.

Ms. Aloysius’ desire to grow rhubarb, peas, carrots and other...