Pat chicken dry with paper towels and season with salt and pepper. In a large heavy flameproof casserole heat oil over moderately high heat until hot but not smoking and brown chicken in 2 batches, transferring with tongs as browned to a large plate. Add wine to casserole and boil, scraping up browned bits until almost evaporated. Add garlic, leeks, broth, tomatoes, zest and chicken with any juices accumulated on plate and simmer, covered, turning chicken once, until chicken is cooked through, about 15 minutes. Transfer chicken to a platter. Add olives to tomato mixture and boil sauce until thickened slightly. Season sauce with salt and pepper and serve with chicken and rosemary orzo. For the Orzo: Bring a 6 litre saucepan of salted water to a boil and cook orzo until tender, about 10 minutes. Drain orzo well, and in a large bowl toss with oil, rosemary, and salt and pepper.