I guess I could've tried to syphon from the fuel filter pipework but I think that would have been very, very slow?
Someone sent me this, apparently from an official Honda workshop manual:-
1. Remove the fuel gauge sending unit. 2. Using a hand pump, hose, and a container suitable for fuel, draw the fuel from the fuel tank.
Fuel Gauge Sending Unit Replacement 1. Remove the fuel fill cap. 2. Fold the rear seat and rise the seat cushion. 3. Remove the access panel (A) from the floor. 4. Disconnect the fuel pump 5P connector. 5. Disconnect the quick-connect fitting (C) and hose (D) from the fuel tank unit. 6. Remove the fuel tank unit (A). 7. When connecting the fuel tank unit, make sure the connection is secure and the suction filter is firmly connected to the pipe.