My FL2 TD4 AUTO (34000 mls) is making a slightly odd noise which seems to be coming from the front axle when the car is stationary but still in Drive.

If the car is in Neutral, all you can hear is the usual clatter of the diesel engine, but keep your foot on the brake and move the gearlever into Drive and there is an altogether higher pitched clattering sound in the background, (not a whining sound)

Anybody got any ideas? (Already replaced the rear diff under warranty last year)

Thanks