No the noise is only audible through gears 1-3.
The engine however is really noiseystationary after a 20 mile run however returns to the standard Lexus 220d tick over with the clutch depressed.
Thanks really appreciate your responses! Helps me sleep better lol!! What ever it is still want to keep the car, I thought my Stype was comfy but surpasses it for comfort, half wish I brought the petrol though although mpg scared me right off!