A controller for a gas turbine wherein the gas turbine includes the compressor arranged to operate at a rotational speed n, the combustor and the fuel supply includes the first fuel supply and the second fuel supply, wherein the compressor is arranged to provide air to the combustor at a steady state air mass flow rate mss and wherein the fuel supply is arranged to supply fuel at a fuel mass flow rate mtotal to the combustor. The controller is arranged to, responsive to the load change ΔL to the load L, control the fuel supply to supply a proportion Z of the fuel mass flow rate mtotal as a fuel mass flow rate mfuel pilot via the first fuel supply based, at least in part, on a combustor mass flow rate mt.