Craig/Chris
Thanks for the advice. Box was new.
So, clamped the crownwheel in vice (with jaw protectors). Got pry bar between flange and collar. Gave the end of the driveshaft a soft tap and bingo!
It all then slid straight out.

I left the circlip on and pushed driveshaft into new diff. Is that right?

I bolted the Quaife to the deeper dished side of the crownwheel - I am now just doubting myself. Is that right?

Thanks
Steve