I drove to the garage and after the drive and a bit of idling, it sarted to splutter at 2700rpm. They looked over the engine, but with there being nothing obviously amiss, they have suggested a diesel specialist, but suspecting air being drawn into the system somewhere. We left it alone for 10 mins and when it was restarted we could not get the syptoms again

I havent put the wrong fuel in, but could have had a bit of muck in the system, and I am confident its not the manifold studs - no squealing and the noise was only at idle where the belts were slipping.
I have cleaned out the banjo filter (was a bit mucky, but not too bad), and running some injector cleaner through it (well there has to be some magic fix that you can pour in

This is about all I can do as the specialist cant look at it for a few days and me and my son are supposed to be camping / kiting on the weekend and I dont fancy sleeping in a bare van or an awning.