I'm having a hard time finding a phrase I'm contended with in regard to a sole item. I tried using "the only one" but for some reason it rings as referring to a person, not an item (but hey, maybe it's just me). I guess an instance is in place to describe my problem precisely:
The pink plate wasn't the only one covered in grime.
The Lansdowne portrait wasn't the sole hung on the vast wall.
The first sounds, to me at least, as talking about a person not a plate. The second sounds plainly wrong, but then again if I insist on keeping "portrait" adjacent to "Lansdowne", how can I possibly write "portrait wasn't the sole portrait". These are just two examples.
Just to make things even clearer, I don't want to use "the only item" because I'm talking about an item out of the same set of items. The pink plate is stationed among other plates and no other cutlery, the first sentence is to convey the idea that some other plates (if not all) are also covered in grime (but plates only). The Lansdowne is hung among other portraits, but not among other canvases of things that are not people - portraits only.