Fuel flow (Q) to a gas turbine engine (11) is regulated by a fuel control (10) responsive to a demand signal (ND4) which is derived from a speed error signal (Ne) proportional to a difference between an input speed demand (ND1) and a shaft speed (NH) of the engine (11). During large decelerating changes in input demand (ND1) both a biasing signal (B) and a rate-limiting signal (D) are generated and result in a rate-limited demand signal (NDL) from which the final demand signal (ND4) is derived. A filtered signal (NHFILT) is derived from the engine speed signal (NH) and is dependent on the magnitude of speed error (Ne). If engine speed (NH) falls below that indicated by the rate-limited demand (NDL), the final demand (ND4) becomes equal to the filtered signal (NHFILT). The filtered signal (NHFILT) lags behind during deceleration and can thus provide a correction which is dependent on the speed error (Ne).