Job done. Spring clips didn't break when I took them off and seemed to be in pretty good nick so I put them back on. Much quicker than Jubilee clips.
After flushing out the system and refitting the hoses I only managed to get around 3.5 litres of coolant back into the engine.
This was after running it until the bottom hose got hot indicating that the thermostat had opened. The return from the heater was also hot, so pretty happy that there are no airlocks in that part of the system.
Haynes says that the cooling system holds 6 litres. Any ideas?
It's pretty cold (and wet, no garage

) out there today so the fan didn't need to kick in. Temp gauge well below half way.