On leaving work at 4.30 this frosty morning, with my mind on other things, i started the old girl before the heater plugs had done there bit, as in the light going out, it started straight away, and it didnt have its usual TD5 clattering when cold, i am wondering if its to do with only having 4 glow plugs!!!! and all cylinders were equally cold
Give it a try

You use preheat? Wow....... I never use that on mine and never have any problems..... maybe I should try it and see what happens