Following a post on this site, I contacted LR and asked them to carry out this modification which they did under warranty.

What they wouldn't tell me was whether or not this would have caused damage to the turbo/engine over the long term if the modification had not been carried out.

The car smoked under heavy acceleration due to oil not draining away from the turbo fast enough, and was instead forced into the exhaust system, although I'm unsure how this actually happens.

Does anyone here know whether or not this could have caused long term damage?