To paint or not to paint?

[ThatsS0Fetch]

LO has ripped the wallpaper off the chimney breast wall. (Its not the actual chimney breast but the small wall next to it. ) when I say wallpaper it's wallpaper that has been painted on top of by previous owner. I have no idea what colour paint he's used and have previously tried colour match paints on another room but have never got the correct shade.

Is there any way to cover it with out having to repaint the whole wall? The actual area that needs covering is approximately 50x200cm from skirting.