Well it looks like my leak might be this same plug that nino_nino mentioned in his post copied below (I hope it is).
I've done ~150 miles this week since washing the engine off, and oil has made it back down to the sump again, so it's more than just a weep imo.

The front of the block is wet, and it appears to be from roughly this plug area and down.
I was starting to think it might be the front crankshaft seal but really hope it's not.
It is real tricky to get a decent look, but I think another good wash and some uv dye as suggested by gonna go double r, plus a short drive might pinpoint it.

Guess what I will be doing at the weekend

nino_nino wrote:

Greg, i had leak in front and after long search located the culprit, it was plug on the top of the oil pump. What I did was to loosen the plug as far as will go apply some silicon and tigtend, problem solved. If not there, leak may be from steering pipe/connection.

pic. of plug.

I didn't manage to clean this area fully, but it shows how wet it is.

Hey John,

Sorry to revive old thread, but I’m currently dealing with what I think is the same. Did you fix this yourself as per the original Nino Nino suggestion ? If so question, what voodoo magic did you do to get in there to loosen it and then get silicon around it ?

I’ve been eye ballin it all day, air intake hose out gives a reasonable line of site, but just can’t figure how I’ll do this without taking anything else out