McAlmont & Butler
Speaking of Duffy, Bernard Butler produced a couple of the songs on her album Rockferry. Not only that, but David McAlmont provided backing vocals on two of the songs.
This pleases me greatly, as one of my favorite albums from the 1990s is the album Butler and McAlmont made together, The Sound of McAlmont & Butler. A couple of months ago I was inspired to dig it out of a box and rip it, and I've been listening to it obsessively ever since.
While the two of them created some incredible music separately (Butler in Suede, and McAlmont both solo and with Saul Freeman as Thieves, whose "Unworthy" is one of my favorite songs of all time), I like them best together, where they created two of the best pop songs of the 90s: "Yes" and "You Do".
Here's "Yes" in all its soulful, operatic glory: