I saw this today on a political blog.

Problem:
The possessive apostrophe after “years” does not belong there.

Explanation:
The phrase “years of experience” translates to “experience’s years” — just as “friends of Jim” and “Jim’s friends” are equivalent.

So, “years’ of experience” would translate to “experience’s years’” — leaving us wondering what the plural noun “years” is meant to possess with its trailing apostrophe.

It seems that the author fell prey to hypercorrection, using both the possessive preposition “of” AND the possessive apostrophe to indicate experience across the years.

Solution:
“From years of experience in primaries”

I saw a phrase like this the other day.

Problem:
The possessive preposition “of” before a noun should not be used with a possessive apostrophe-‘s’ after the noun.

Explanation:
The phrase “friend of somebody” translates to “somebody’s friend”.

So, “friend of Jim’s” would translate to “Jim’s’s friend” — a meaningless concept.

It seems that the author fell prey to hypercorrection, using both the possessive preposition “of” AND the possessive apostrophe-‘s’ to indicate friendship with Jim.

Solutions:
“friend of Jim”
or
“Jim’s friend”