A control system is provided for performing staging control of a multi-stage combustor of a gas turbine engine. The fuel is fed to the combustor by a fuel supply system comprising: a plurality of fuel manifolds distributing fuel to respective stages of the combustor, a fuel metering valve operable to control the rate at which fuel passes to the fuel manifolds, and an actuating arrangement which splits the fuel flow from the fuel metering valve between the fuel manifolds. The control system includes a fuel pressure sensor arrangement which senses the fuel pressure at entry to the actuating arrangement, and/or in one or more of the fuel manifolds. The control system further includes a controller which repeatedly: calculates a fuel split between the fuel manifolds based on the sensed fuel pressure(s), and issues a command signal to the actuating arrangement to implement the calculated fuel pressure-based fuel split.