here is the news ,,,,
head gasket ok , water tested and ok, compression also ok.
Garage been quite good, they say whats already been posted, either a worn cam or blown value as "its blowing back down the air inlet".
They said the next step id to strip BUT have recommended I take it to a Range Rover specialist in earlswood (solihull).
Off to garage in morning then down to earlswood ! keep you all posted ! and thanks again for the help and advise
If all the compressions are good, and within 10 psi of each other, then i would be inclined to plump for worn exhaust cam.