Thanks - I did look in the Haynes manual but it wasn't very clear. Something which has puzzled me slightly, was that it says to remove a hose which carries oil (and to put a container under it). Why would there be an oil feed to the radiator??
There was no corresponding picture for this comment, so I have no idea what it's talking about.
 I'll be doing this on ramps!
I know the haynes manuals are not as good as they used to be (or is it cars are more complicated?) nope, they are definately not as good
There is a water-cooled oil cooler with its own thermostat,- the thermostat is on the waterpump, it comes out of the thermostat, through the oil cooler,(its a big square block under the pump) then back to the radiator, (small diameter black rubber hose, low down on the right-hand side, when standing, looking into the engine bay ) only water flows through it, the oil stays in the oil cooler
When you refit the radiator, you need to get the engine hot enough for both thermostats open (the main thermostat and the oil cooler thermostat) to properly bleed the system- the water level can drop when the thermostat/s open - its hard to get the temp up in these cars, i fill it with the required amount/ concentration of anti-freeze, then take a couple of litres of distilled water with me, go on a hard, uphill run, keeping an eye on the temp gauge, if i get it over 1/2 way i check the expansion tank and top it up, i check the radiator hoses and the "oil cooler" hose to make sure they are hot - and top up if nessesary - if the "oil cooler" hose is cool the oil cooler thermostat has not opened yet - it takes some warming up!