As I had a spare hour on a nice dry Sunday afternoon I decided to have another play around.

Removed bottle cap,fitted pressure adaptor and pump system to 19 psi and stood back and waited

.After a few minutes noticed a slight puddle forming on the inside of the plastic engine under tray,so feeling a bit better I was onto something decided to have a good search around with a LED torch

.Was also relieved as atleast that was well away from the likely HG area

.After tracing the height of the coolant drop and where lower position of coolant seemed to be appearing from eventually found slight moisture around the top hose where it connects to the stat transfer pipe.Further checking found that the spring clip wasn,t very tight so removed the hose and replaced with all that I had to hand being a new jubilee clip and tightened with socket.

Bingo....the drip has stopped and holding steady 18psi for over 1 hour now without any drop ,so fingers crossed that may have atleast been part if not all of the problem and been bugging me for months now

.Doudt I would have ever found it without doing cold pressure test as coolant is just getting blown back when driving onto a hot exhaust and causing the burning smell I have had when topped bottle.

Pointers on level seem to bear out the problem as dropped coolant level is consistant with position of the transfer/top hose point..being quite a bit higher than HG joint.

My fingers are crossed that may have been the problem and a fairly simple fix although I will monitor it during this week and see what happens.I do need to do some other stuff on the engine so will carry out further pressure test when plenum etc are removed but my initial findings look promising so thanks for all who have offered advise and motivation.
Not too happy about top hose to transfer pipe being secured with a jubilee clip now but I suppose if its holding tight then leave it well alone as those spring clips are a PITA to get at in that restricted place.