The Official App of Halcyon London International School. Learn more about the school and access all the school information you need as a community member or a visitor. Our new login function ensures a personal experience with Halcyon. We are constantly in development, so keep an eye out for updates. ABOUT HALCYON Situated in Marylebone, London, Halcyon is central London's only not-for-profit International Baccalaureate (IB) school, leading the way forward in education. We inspire students to em