Hi - Sorry I didn't read your first post thoroughly - I was dogsitting my daughter's dog and it was being a bit of a nuisance (nothing unusual there, he'd already escaped this morning, fortunately a neighbour and his wife were outside their house with another neighbour and they managed to catch him).
I've looked at the crew names that have been transcribed and your ancestor is not yet listed. (I should say that as the Dorset ones are on Ancestry, I and my fellow transcribers will not be doing these). There was a John Norris from Cardiff, but he was born about 1879 and was an assistant steward and bandsman on a ship called Balmoral Castle. Was that another ancestor?
I looked on Ancestry and, although the transcribed ages differ on the 2 occurrences of his name, I think the 2 are the same man and his age was mistranscribed on one of them.
I've looked up that particular ship Orleans and it was not a P & O vessel. It was registered in Poole in 1876 (built in South Shields in 1874), and was owned by The Loire and Thames Transit Co. Ltd, 150 Fenchurch St, London. I've googled that name and it doesn't appear to have been taken over by P & O.
By the way if you go to the crewlists and next to his name, you click on View Images, then once the image comes up go back one page and you'll see the details of the particular voyage. In these 2 cases, it doesn't give much useful info, apart from the fact the vessel was going from London to St Nazaire. It was also quite a small ship, only 271 tonnes net.