Annoying Rattle/Vibration

[Matt Haigh]

My 2010 HDi XTR has recently started an annoying minor vibration/rattle that seems to come from somewhere behind the drivers side instrument panel, it occurs as the engine goes through the approx 1000rpm speed range either in neutral with a small bit of throttle or on acceleration / deceleration through that engine speed. I've tried pushing all the bits of trim to no avail and checked everything that looks possible in the engine compartment; aluminium a/c lines, washer bottle etc. 

I'd appreciate suggestions on anything else to check, thanks.

Matt