Thanks for the replies.

On start up no noise apart from a slight whining noise that also happens on acceleration in neutral, but goes away once I drive away - I thought this was normal for a car with this much mileage.

The noise only appears after a 30 - 40 minute drive, then when I park the car that's when I hear it. Can only be heard when sitting in neutral. And is prominent from under the drivers door under the bonnet.

The best way I can describe the noise is that it sounds like a diesel car/van running and not a knock/tick.

And the whining sound sounds like a diesel car/van when accelerating. (not the misses since she is in the house )

The car drives fine, very fine

Is it just noisy injectors or/and worn engine?