The "blue hour" is the name given by photographers to the hour or so after sunset or before sunrise. During this time, the sky has a deep blue tone to it and can produce some remarkable results. This is the time for long exposures and a fair bit of patience. This one looking over to Sydenham Hill with its television masts showing off their red warning lights was taken with a 25-second exposure, just time to catch the train in the bottom left as it was pulling out of Sutton station en route to Carshalton Beeches...