A fuel transfer adapter for a fuel cartridge, the fuel transfer adapter comprising: an adapter body; at least one fuel filling channel through said adapter body for the passage of fuel from a valve of the fuel cartridge to a fuel tank of an appliance through a filling port of said fuel tank; a fuel cartridge engaging portion at one end of the adapter body, for engaging the adapter body with the valve of the fuel cartridge; and, a port engaging portion at the other end of the adapter body for releasably engaging with the filling port, whereby the fuel transfer adapter incorporates at least one vent for the passage of vapour from the fuel tank to the atmosphere, said at least one vent being configured, in use, to transfer vapour displaced from the fuel tank by the fuel entering therein to the atmosphere.A method of filling a fuel tank of an appliance comprising the steps of: docking a fuel cartridge equipped with a fuel transfer adapter to a filling port of an appliance; applying a push force between the appliance and the fuel cartridge to open both a port filling valve and a fuel cartridge valve; applying a further push force between the appliance and the cartridge to create a fluid-tight seal between a compliant rim of the fuel transfer adapter and the filling port, and to create a fluid-tight seal between the sealing lip of a port engaging portion of the fuel transfer adapter and a wall of the filling port; allowing fuel to transfer from the fuel cartridge to the fuel tank of the appliance, and displaced vapour to transfer from the fuel tank to the atmosphere through a vent in the fuel transfer adapter; and, undocking the fuel cartridge from the filling port.