Getting off Mt Drake.
Abseiling the Corsair. This is probably the easiest and quickest way off – provided you have two 50m ropes. From the summit of Drake scramble west along the summit ridge for 55m to a large (~3m) rock, shaped as though it has a cap (it also has a cairn atop). Turn right and descend north for 50m of easy scrambling, following cairns. Turn west and drop down a gully/corner to a double bolt belay. From here rappel to the top of the West Wall and continue abseiling down the equipped Corsair route to the base of the wall (5 full pitches). Continue abseiling to the Satellite Buttress and the névé, as required.
Abseiling the Bamaphone: This could be a useful alternative to the Corsair descent if you only have one rope. From the summit of Drake continue past the large rock (cairn atop) until the top of the Spanish Armada route can be seen. The next gully is the Bamaphone route, abseil down it. From the foot of the route cross the snow slope to the base of the West Wall and continue abseiling (~3 more pitches to the névé).