A fuel pumping unit having a low pressure centrifugal pump and a high pressure centrifugal pump, in use, the low pressure centrifugal pump supplying fuel at a boosted pressure to the high pressure centrifugal pump for onward supply to a fuel metering unit; the pumping unit further having a drive input which drives the low and high pressure centrifugal pumps; pumping unit further having a positive displacement start pump which is driven by the drive input; and the pumping unit further having a selector valve which is configured to selectably provide a high pressure mode, a low pressure mode and a start mode, wherein: in the high pressure mode the low pressure centrifugal pump supplies fuel at the boosted pressure to the high pressure centrifugal pump for onward supply to the fuel metering unit; in the low pressure mode the fuel supply from the low pressure centrifugal pump to the high pressure centrifugal pump is shut off such that the high pressure centrifugal pump runs dry and the low pressure centrifugal pump supplies fuel to the fuel metering unit; in the start mode the low pressure centrifugal pump supplies fuel at the boosted pressure to the positive displacement start pump for onward supply to the fuel metering unit fuel, and the fuel supply from the low pressure centrifugal pump to the high pressure centrifugal pump is shut off such that the high pressure centrifugal pump runs dry; the drive input is a single input drive shaft from an engine accessory gearbox, and a gear arrangement is operatively located between the single input drive shaft and the low and high pressure centrifugal pumps such that the low and high pressure centrifugal pumps are driven at different speeds by the drive input, and such that the positive displacement start pump is driven via the gear arrangement; in the high and low pressure modes, the selector valve recirculates fuel between the positive displacement start pump and the selector valve. in the high pressure mode the low pressure centrifugal pump supplies fuel at the boosted pressure to the high pressure centrifugal pump for onward supply to the fuel metering unit; in the low pressure mode the fuel supply from the low pressure centrifugal pump to the high pressure centrifugal pump is shut off such that the high pressure centrifugal pump runs dry and the low pressure centrifugal pump supplies fuel to the fuel metering unit; in the start mode the low pressure centrifugal pump supplies fuel at the boosted pressure to the positive displacement start pump for onward supply to the fuel metering unit fuel, and the fuel supply from the low pressure centrifugal pump to the high pressure centrifugal pump is shut off such that the high pressure centrifugal pump runs dry; the drive input is a single input drive shaft from an engine accessory gearbox, and a gear arrangement is operatively located between the single input drive shaft and the low and high pressure centrifugal pumps such that the low and high pressure centrifugal pumps are driven at different speeds by the drive input, and such that the positive displacement start pump is driven via the gear arrangement; in the high and low pressure modes, the selector valve recirculates fuel between the positive displacement start pump and the selector valve.