I appreciate the replies so far; they've given me a few more things to search for, but still no luck. The aim is not just to make the objects look better, but also to stay as close as possible to the original styles.
By-the-way King....what game? That might even lend credence to your quest!
The objects are from a game called Thief: The Dark Project, released by Looking Glass Studios in 1998 (with a sequel in 2000). The 'internal' name of the 1st chair is Gold Chair, but the original gold colour seems to have got lost when the file was made. It looks to me like the picture on the back rest is a man on a horse.
Does anyone know if there's a name for the style of the 2nd chair? And could it be from a church?
One other possibility is that those textures are actually from buildings or doors or panels etc, but let's hope not.