Five partners and up to 25 staffers in the 200-person London office of New York City-based architect Kohn Pedersen Fox Associates have left to start their own practice, PLP Architecture. They include Lee Polisano, KPF’s former president. The move comes after the five made a failed attempt in July to buy KPF’s U.K operations, says its chairman, A. Eugene Kohn. The firm’s 13 shareholders at the time rejected the offer, he says. Polisano says the new firm will allow the principals and employees to explore new opportunities, which he declines to disclose.