Smashing photo

if only my engine was out on a stand, it would be so much easier

As you know, space around there is about as tight as you can get

.
Anyway, I'm now encouraged enough to try to get the pump off in situ, and if it doesn't, then off with the drive sprockets.
I've already bought 5 Litres of G30, so a Radiator flush and a change was on the cards, and as and when the pump is finally out, I'll be able to see how it seals.
As an aside, the water pump I had left over from my 1.8 is identical to this 2.4 one (other than the pulley dia), but that one had cast iron impeller, whereas this new one is made from formed thin steel plate. Hopefully the antifreeze will stop the plate from eroding away
In actual fact I bought a full Gates Kit comprising of the Belt, pulley, tensioner and water pump, which is why I was surprised there was no O ring/gasket provided with it.