My 1996 diesel bongo went through the MOT very nicely the other day

There has always been a little oil around the rocker cover which I have not lost sleep over (I've read a few posts on the forum about this and it sounds quite common).
I have however been keeping an eye on a further oil leak which seems to be coming from somewhere towards the front of the engine on the drivers side. I have been concerned that it might be the head gasket or the cam seal (both have been mentioned on the forum ) but on closer inspection today I found oil leaking from somewhere near the bolt attaching the inlet manifold to the cylinder head by cylinder 1. I had a closer inspection and the bolt is intact and dry - no hint of oil.
I have uploaded some photos here :


Should I be worried - it seems to be an insignificant amount of oil and I'm not having to top up at all?
Any ideas what needs to be fixed and how I should go about it?
Is this a common problem?
Have I missed any posts on this matter?
Any advice and/or suggestions much appreciated.
James