[garybee]

Poor starting diesels are often due to glow plug issues. Those engines commonly have faults with the glow plug controller which doesn't necessarily turn the.engine check light on. Worth getting the fault codes read.

 

[garybee]

Have had an old fuel line seeping overnight and drawing air in the system. Same symptoms as you fine all day just didn't want to start in the morning.

Yep, a duff fuel line can cause similar. As can a faulty fuel pressure regulator. Easy to check for this though, just cycle the ignition on and off a few times (pausing to allow the fuel pump to prime) prior to cranking. This could also allow lazy glow plugs to heat up though so if it starts sharply you still don't know the cause without testing the rail pressure.