Other Freelander TD4 HSE Starting problems

Hi, I have a Freelander TD4 HSE S/W 2005 Diesel with a BMW engine. It has starting problems. Sometimes when you turn the key it won’t fire or starts reluctantly and runs a bit lumpy and won’t rev up when you press the accelerator. On a couple of occasions it hasn’t started at all and flattened the battery with no attempt to fire – like there is no fuel getting through. Eventually with another battery it did start. When it does start, if you stop it without warming it up, it is even worse to start. Once warmed up/hot, it seems to start better, although I am never confident it will start. It is often hesitant to fire up first time. Any help or suggestions welcome. Thanks Adam.

High pressure fuel pump regulator O rings are a common cause of non starting.
Also the high pressure fuel rail sensor can give trouble.