Turnover but no fire until throttle applied

I have read lots of threads that say you should not apply the throttle until the engine fires as this would affect the engines cold start.

It was -3 C this morning when I tried to start the 300 tdi - the engine turns over fine with the starter but without any throttle is very reluctant to fire.

Has new battery, new starter, new earths to chassis, bellhousing, starter and block....

Would be very grateful for some counsel....

Read some off the newer threads about non starting, funny but they all are 300 tdi's.

Removed a couple of glow plugs -- they were buru components and caked in oil n crud. Tried to pass 12v across terminal and earth case using spare car battery - both dead no heat at all ....

Are the cheap ones sold at craddock's any good compared with the Lucas or ngk ones you can get a set of 4 for about 32 quid of fleabay?