I’m getting a rather awful fumey smell in the cab when I reverse the car. It comes and goes almost immediately and doesn’t linger when the car moves forward but is pretty smelly when it appears. There is also a nasty noise under initial load which is most noticeable in second when building up to changing into third. If I was to offer a description I’d say it was almost “leaking exhaust” like but seems to be worst at biting point. 
 

Im wondering if the two are somehow related but if not if anyone has any pointers as to what to check I would be most grateful. 

Sounds like a GPF doing a regeneration cycle?

 

Search here for GPF and you will find a few results.

Cheers. The weird thing is I only smell it when reversing and when I stop the exhaust fumes smell normal and there’s no strange smells in the engine bay. 

It could be gearbox related, mostly it's guesswork for us remotely trying to diagnose.

When reversing the cabin air intake flaps should close.   If there is an issue it might lay with that. 

Get it looked at under warranty