It has been written that the s suffix was also used by people that had a “master” and they would adopt their masters surname, trade or first name with the suffix. For example the worked for the Smith, they would become Smiths.

Trouble is I can’t remember where I read it, but I also recall at least two people that were heavily into genealogy telling me the same. It might have been

https://www.routledge.com/A-History-of-British-Surnames/Mcki...