Whine or trumpet sound or whale sound and MOT

[Ed3]

Thanks Mike Noc, I will go by your suggestion and order a correct fuel filter from dmgrs regardless of the noise.

But it so happens that this morning I was with a lady who is not interested in car mechanics but who could instantly tell when the whine/trumpet noise starts. So it is something loud enough that needs fixing.

Having chance to today listen at the engine bay while someone revs the car, - the whine/trumpet sound is in, by or underneath the diesel fuel filter (the main standard fuel filter that is clamped to the battery casing).

If the noise is not around the fuel filter it is something about 2 inches behind towards the bulkhead and very low down, - possibly a turbo pipe. But I will fit a dmgrs correct fuel filter by Tuesday/Wednesday and see what that does.