Hi Darren
I followed the steps and voila, although my scene is currently rendering at 08 photon mapping fine, I saw from a quick render that the desired effect is happening: man, it's a good feeling

(Actually I see it's all in the Getting Started Manual which I should have remembered from my reading

but sometimes we slower ones need an extra prod!)
Could you please clarify something for me: when you have edited materials, are sending to render and accept the changes as permanent it is only whilst in KT and are refining your renderering that the changes are permanent? So if you go back into SU to make a major change to your scene and then back into KT you have to go through the whole editing materials process again before rendering. IOW can't you keep various of your previously edited materials permanently permanent? It's very tedious having to go through the whole lot again. Sorry, is that clear as mud?
Thanks for your kind assistance (and everyone else's considered responses)
Deborah