Freelander won't start... non return valve?!?

Hi All,
Yet another issue with my freelander!
Over the last few months its struggled on start its turned over but really had to put my foot on the accelerator to push the fuel around and even if it did start if I didn't push the fuel round it would conk out. This had got progressively worse, a friend who is far more mechanically minded than I suggested it sounded like the non-return valve. Anyway a few months of this issue and now it finally will not start, it turns over but will not ignite at all. I have been looking for said Fuel non-return valve and can not find it suppliers wise or even on diagrams of the car, any suggestions please?

Its a 03 (Old version) TD4 Auto

Thanks in advance
K

TD4 won't start fault diagnosis...

Probably the High Pressure Fuel Pump (on the engine) O ring on the pressure regulator (cheap and simple fix).

Can you hear the lift pump (under rear wheel arch for your year) prime when you turn the key on, and does it stop after a few seconds?

Could also be the fuel pressure sensor harness (an uprated one is available pn YMQ503320) or a crank/cam sensor (dunno which is used for starting). If its also smoking a lot, could be injectors.

That's my thoughts.