The Brighton Main Line is a divided in the north into two sections running from London Victoria and London Bridge to Brighton. It is about 51 miles (81 km) long, and is electrified throughout. Nearly all passenger trains are provided by Govia Thameslink Railway which operates the Southern, Gatwick Express and Thameslink brands. A small section has Great Western Railway services, currently sole operator of the line from Gatwick Airport to Reading, Berkshire known as the North Downs Line. The many Sussex services to Central London use the line and generally its branches as do south London, East Surrey and Tonbridge, Kent services.