The annual ballot for a chance to follow Larry through the famous black doors of 10 Downing Street and take a look around the corridors of power is now open. The tour is offered by Open House London, which opens up hundreds of buildings across London for free in September. However, while most are open to just walk in – with some requiring booking – the tours of 10 Downing Street are offered by a free ballot. To enter the ballot, log in (or open an account) here . Bookings for the rest of the Open House events go live on Wednesday 19th August from here.