That's my confusion Richard - there should be no high pressure oil feed near where this leak seems to be coming from.

I'll get and get the mirror further round over the weekend and see. I'll be pissed if the valley gasket is the cause.

It’s not so much the valley gasket, as those badly made end seals. ( shitpart)
I’ve trimmed a few when doings head jobs, had one leak on my previous engine, literally coated the complete underneath of the car front to back ( was on motorway a lot ) had to gunk and jetwash underneath.
Not a huge job to do if it is them, couple of hours tops. Just more a PIA .