I couldn’t help but hear Gollum as I read this thread.
I put in the extra s, because I was taught that way and because I pronounce the s. So I do say James’s as “Jameses”, not “James”.
Yes, I was taught that for singular proper nouns, one adds the s whenever it is pronounced: James’s book, Marcos’s car, Jacques’s hat (that’s an extra s too, because normally the s isn’t pronounced).
One would only omit the s where it isn’t pronounced, as with certain classical or biblical names (in Jesus’ name we pray).
As noted elsewhere on these Boards previously, there is a St James’s Park in London which is always spelt that way nowadays.
An exception is a single name board at the underground station (at the eastern end of the eastbound platform) which omits the additional S. This is deliberate, as it shows the station name as it appeared up until the early 1950s, when London Underground crystallised its policy on apostrophes.
This is how both our in-house editor (me) and our contracted editor/proofreader treats it as well. We use the Canadian Press Stylebook.
Let’s have a look at The Canadian Style. reaches up from sitting position to easily accessible copy leafs through
Here we are, page 141. (1997 ed.)
Cite? I’m away from home, so don’t have the AP Manual of Style, but I remember the AP rule as add only apostrophe for possessives of proper nouns ending in “s.” For common nouns, add apostrophe-“s” unless the next word begins with “s.”
It is correct in AP Style for the possessive of James.
ETA: Here’s the page from the AP Stylebook that addresses possessives of names and singular nouns ending in s.
AP sez: proper nouns ending in “s” just get an apostrophe. Common nouns ending in “s” get an “apostrophe-s” (unless the next word begins with “s.”)