Does anybody know what/if there is a seal here! I'm not on about the rocker cover, but the bit below it? In line with the cam seal, just above the writing, you can see black stuff coming out, earlier today oil was seeping out. I've refit the rocker cover as I believe that was the fault but just double checking. It's a TD5.

Iirc the fact them two set of numbers match means that a matched part as the cam bearings are line bored into the head and the top frame, I would hazard a guess theres wellseal or some other thin sealant used in that joint.
I assume you have tried a new rocker gasket?

That's the join that needs 'rolled' high temp silicon-type sealant, which I did when replacing the head, and it pee's oil (from the front in my case) like its going out of fashion..... was fine for a year or so, getting worse by the month now, and I'll be well chuffed if I have to dismantle just to renew sealant....grrrrrr. New gasket and head bolts anyone.....?? Will try nipping up the bolts around the area first (observing some sequence and torque settings I spose along the way.....) Ho hum, A