Walham is an English village, situated north of Gloucester, on the banks of the River Severn, just off the A40 road and Sandhurst Lane, 153 km west of London.
A National Grid substation, providing power to half a million homes and the Government Communications Headquarters (GCHQ), is situated at Walham. The substation came to national prominence in July 2007, when it was threatened by a major flood. The fire service and military stopped the flood waters two inches below the height at which the plant would flood. This struggle with nature was dubbed the "Battle for Walham" in national newspapers.