Yesterday at work I had taken the RR in to pick some things up... and as its quiet - I had another look around for this odd noise. Still none-the-wiser sadly. Found some cooler lines that were touching in places, so put some hose around those points in the vague hope it might be it. But alas, not that easy.
I think it might be time to start tearing into it - starting with the RH bank exhaust header. While I'm at it, I might pull the whole inlet off and reseal the valley, again. See if I can stem the oil that is making its way down onto the starter motor - might now also be from the rocker cover on that side, but it wasn't to start with.
Southampton with a Nanocom for Thor/GEMS P38s
1996 4.6 HSE, then became a 4.0, now cubed.
1997-8 4.6 HSE Motronic/Wabco prototype vehicle. Now M57 powered. Still auto.