TD5 fluctuating tickover

Is fluctuating tickover normal after startup on TD5. it's as though the ecu is continually adjusting the choke to sus out where best to set it.
Engine runs fine when you drive off.

I'm sure I've heard defenders running like this so am I right not to be concerned over it, or is something needing attention?

td5 has only 4 glow plugs so 1 cylinder doesnt pre heat, so the car sounds rough for a few seconds after cold starting until the cylinder catches up with the heated ones