TD4 starting issues

Having trouble starting, 2001 TD4. Turns over for ages before it catches. It does not smoke and it runs nice and smooth on start up. The glow plug light on the dash comes on but dosent seem to make a difference to starting.
Where to start looking first?

If it's only a problem when cold, glowplugs.

I had this problem intermittently, same thing, would crank for ages but no smoke or other signs.
Also had really poor acceleration - hardly any power below 2000rpm. Scary when pulling out into traffic.
Changed the MAF and fitted a "Ronbox" now all the problems have gone away and it pulls like a train.

I had the same thing even when it was warmed up went out today with it and lost power on it and engine light came on it stopped and would not start so called the AA I had code p1260 and the fuel pump in engine bay next to filter was sticking so they tapped it and it started they said I needed new lift pump