Morris's have been an independent lube manufacturer in the UK for a very long time. They do lots of specialist stuff for the preservation crowd that have open gears and drives on steam engines as well as other more up to date equipment. I would say what they don't know about lubrication isn't worth knowing. Our local motor factors has a database from them of all the vehicles by number plate and all the oils they take plus any alternatives.
Look at it this way, if you follow their recommendations and it fails to do the job, you can go back to them and say 'you told me X and it didn't work' but I would put money on that not happening. Everyone round here uses and swears by Morris's. Their knowledge base is second to none I would say. They do have reps, or at least they used to when I first came across them. Perhaps if you're unsure you could ask for one to contact you or talk over what you've found on the net with their technical. This can't be a new problem and if that's so, they will almost certainly have come across it before.