Answer Yes its a standard cup and cone axle.
I had to unbolt the reaction arm from the chainstay, and unbolt the brake cable from the activation lever arm. This was simple.
Gotchas though - you have to remove the drum brake completely, and the inside cone is recessed so its hard to get a cone spanner on it. Best method is to get the inner cone and lock nut in the right place on the axle, and tighten them together and then do the drive-side cone.
Hub with locknut and spacer removed. Notice there's an awful lot of spoke holes on this thing, I could fit double the number of spokes! :
Drum/hub with brake removed::
Drum shoes, view from the inside. They're not a great fit with some parts worn smooth and other parts never touched the drum. Activation is incredibly simple-the shorter arm is pulled forward by a brake cable, which rotates the shaft. There are lobes on the shaft that push the brake shoes apart, and against the inside of the drum. When the cable pull drops, the two beefy springs pull the shoes back off the drum.