(57) The drop-down lid of a gas appliance, e.g. a cooker hob, operates a microswitch 2 in the circuit supplying power to a solenoid valve 1 controlling the gas supply. A latching circuit 4 acting through a relay 3 opens the valve 1 on closure of the manually operable switch 6 thereby ensuring that gas does not escape immediately the lid is raised if it has inadvertently been closed down on a lighted burner. The switch 6 may be coupled to an ignition switch, preferably with a time delay. A further delay may be incorporated in the latching circuit to ensure that the gas cannot be turned on by a momentary inadvertent closure of the switch 6.