RESTORED QUEEN ANNE houses sell for more than $10m in Cambridge, a small city across the Charles River from Boston. Victorians, brick rowhouses and triple-deckers (three-storey homes, with an apartment on each floor) are all very dear. Rent is high, too. Low-income residents are decently served by public and subsidised housing. But middle-income renters and buyers are mostly locked out of finding a home in Cambridge.