Drop possessive apostrophe for noun ending in s/double s

Question

Most sources I've found state you should add the possessive apostrophe even to nouns ending in s, as in Thomas's and James's, but does this ring true for nouns such as duchess, countess, and marquess? Can one write countess', duchess', or marquess' instead?

Cosmopolitan dropped the possessive apostrophe here. Now, they've also spelled duchess with a capital D, and I'm not sure if that may have something to do with it. They aren't a reliable source anyway, but I'm just wondering if the lack of the possessive apostrophe may be permitted for nouns such as those I've enumerated above?

And would it be acceptable as part of a title (any title) and/or royal title/rank?

I'm mostly interested in the British English perspective.

[edit] I found this article from the Telegraph and they've used duchess's. Same for this link. Shakespeare says Auvergne. The COUNTESS's castle. in The First part of King Henry the Sixth. Sally Gardner's book is titled The Countess's Calamity as well.

Answer 1

It depends. There really is no hard-set rule about this. The general rules are:

1. Singular nouns add 's to form the possessive
2. Plural nouns not ending in s add 's to form the possessive
3. Plural nouns ending in s add only an ' to form the possessive

so we end up with:

1. The frog's ball
2. The children's ball
3. The babies' ball

Adding the ' to the end of a singular noun which already ends in s may cause the reader to mistakenly assume that this is a plural possessive because that is what we usually think. This is compounded by the fact that we are often lazy readers, those who rely on cues to read quickly without having to consider the intricacies of grammar.

To answer your question...yes, you can omit the apostrophe for singular nouns which already end in s, but some people might not be happy about it. Since you asked about the BE perspective, I found this advice from The Guardian:

The possessive in words and names ending in S normally takes an apostrophe followed by a second S (Jones’s, James’s), but be guided by pronunciation and use the plural apostrophe where it helps: Mephistopheles’, Waters’, Hedges’ rather than Mephistopheles’s, Waters’s, Hedges’s.

Plural nouns that do not end in S take an apostrophe and S in the possessive: children’s games, old folk’s home, people’s republic, etc.

Phrases such as butcher’s knife, collector’s item, cow’s milk, goat’s cheese, pig’s blood, hangman’s noose, writer’s cramp, etc are treated as singular.

Answer 2

This may come awfully late, but hopefully is still helpful to someone, somewhere. In British English (I was talking on the phone with my cousin yesterday and the Duchess of Sussex came up, as it is a habit of late) you pronounce Duchess's exactly how you pronounce Duchesses'. The context will hopefully tell you if you are speaking of one Duchess or more than one. I can come up with a couple sentences to confuse one's mind, but they are not likely to occur in the real world. Our language is one of context. I wish at times we spoke German.