Christine Svenningsen, who was married to a party-goods magnate, is selling Belden Island (left) for $3.95million and Jepson Island (right) for nearly $2million. They are part of the Thimble Islands off Branford, which have attracted celebrities and the wealthy for generations. ‘For anybody looking for privacy it’s got great appeal yet it’s very close to the mainland,’ said Clint Rodenberg, an agent at William Pitt Sotheby’s in Madison, which is handling the sale.