A gas turbine engine having: a bypass duct through which air flows, when in use, to provide propulsive thrust; a fire wall that is configured to provide a fire resistant barrier between a first zone and a second zone in the gas turbine engine, the second zone being hotter than the first zone when the gas turbine engine is in use; an actuator that is located in the first zone and is configured to generate a mechanical force when operated; an actuatable device that is located in the second zone and is configured to be actuated by a mechanical force; a mechanical force transmitting device that extends from the actuator to the actuatable device via a hole in the fire wall, wherein: the mechanical force transmitting device is configured to, when the actuator is operated, actuate the actuatable device by transmitting a mechanical force generated by the actuator to the actuatable device; the mechanical force transmitting device includes an elongate element configured to move along a linear path so as to transmit a mechanical force generated by the actuator to the actuatable device, and an elongate housing or shell, the elongate element being configured to move along a linear path within the elongate housing or shell; and the gas turbine engine includes an off-take device for extracting cooling air from the bypass duct of the gas turbine engine and for supplying the extracted cooling air to the elongate housing or shell when the gas turbine engine is in use. a bypass duct through which air flows, when in use, to provide propulsive thrust; a fire wall that is configured to provide a fire resistant barrier between a first zone and a second zone in the gas turbine engine, the second zone being hotter than the first zone when the gas turbine engine is in use; an actuator that is located in the first zone and is configured to generate a mechanical force when operated; an actuatable device that is located in the second zone and is configured to be actuated by a mechanical force; a mechanical force transmitting device that extends from the actuator to the actuatable device via a hole in the fire wall, wherein: the mechanical force transmitting device is configured to, when the actuator is operated, actuate the actuatable device by transmitting a mechanical force generated by the actuator to the actuatable device; the mechanical force transmitting device includes an elongate element configured to move along a linear path so as to transmit a mechanical force generated by the actuator to the actuatable device, and an elongate housing or shell, the elongate element being configured to move along a linear path within the elongate housing or shell; and the gas turbine engine includes an off-take device for extracting cooling air from the bypass duct of the gas turbine engine and for supplying the extracted cooling air to the elongate housing or shell when the gas turbine engine is in use. the mechanical force transmitting device is configured to, when the actuator is operated, actuate the actuatable device by transmitting a mechanical force generated by the actuator to the actuatable device; the mechanical force transmitting device includes an elongate element configured to move along a linear path so as to transmit a mechanical force generated by the actuator to the actuatable device, and an elongate housing or shell, the elongate element being configured to move along a linear path within the elongate housing or shell; and the gas turbine engine includes an off-take device for extracting cooling air from the bypass duct of the gas turbine engine and for supplying the extracted cooling air to the elongate housing or shell when the gas turbine engine is in use.