Long story short, Had the cambelt replaced on my Disco 1 300tdi by a local workshop, the full kit was used along with the modified idler to prevent belt run-off. Fast foward 9000km and I'm driving to work and notice a cloud of white smoke behind me and the temperature gauge heading north so I pulls over and shut the engine down before it climbs into the red, had only travelled about 10 km at this stage. At this stage I'm thinking classic head gasket failure. Got the Disco transported to another workshop (this was just before Xmas and the original workshop was too busy to look at it) Anyhoo, the head is pulled off and the head gasket is fine however it's found that there has been valve strike on all four piston crowns from the inlet valves and the rocker shaft is snapped below a pedestal. The head was sent for crack testing and sure enough there is a crack inside No2 inlet port. Finally got hold of a new (generic) head and along with a self taught engineer we set about replacing the cylinder head, we removed the timing cover and found that although the injector timing was fine, the valve timing was out by one tooth. What I now would appreciate is confirmation from a VM or Tiffy to confirm my theory of the train of events being that when the cambelt was replaced the valve timing was either not checked or was incorrectly adjusted and over time with carbon build up this in turn placed strain on the rocker shaft eventually breaking it, at the same time this would have stresses on the rocker shaft pedestal which in turn caused the head to crack. Thanks in anticipation.