When the state’s highest court ruled last month that the owners of Stuyvesant Town and Peter Cooper Village had illegally raised rents for tenants whose apartments should have been rent-stabilized, the case was widely expected to have far-reaching effects on city housing policy. At London Terrace Gardens in Chelsea, a group of 10 rent-regulated buildings, building owners are already feeling the Stuy Town ruling’s impact. Eleven tenants there filed suit against their landlord last week in New York’s state supreme court. They charge that the landlord, a group of families who have owned the complex since the 1920s, did not re-regulate their apartment rents even after receiving a city tax abatement for renovations in 2003. As many as 300 units could be affected, according to the class action suit, which the tenants’ attorney expects more plaintiffs to join.