Defender 3.5 V8 unusual oil leak

Howdy..
So here goes nothing...
My 98 defender 3.5 V8.petrol. is eating engine oil...
1. The left bank 2&4 plugs are oily
2. Left Exhaust manifold is oily and oil trickles down the down pipe..
3. There is a drip in the driveway regardless of whether parked for days or running..
4. There is oil on every flange on the exhaust tail pipe
5. No trace of Oil on the Right ( dip stick ) bank side..."Strange"

So far New Valley and tappet cover gaskets fitted- No change..
Could anybody point me to the right direction please..
I will post pictures tomorrow...
Your comments are appreciated...

Stem seals i'd hazard

I'm guessing it smokes like a train..

As @Henry_b , this sounds like stem seals. Before diving in it would be worth asking on the v8forum.co.uk + if heads need a proper refurb' now would be the time to do it. If not refurbing at home can recommend sending heads to Peter Burgess http://www.peter-burgess.com/page18.html ; especially his Econotune V8 heads