Old White, quite simply, is the most historic of Farrow & Ball whites. It's part of the Traditional Neutrals group; Lime White, Off-White, Old White and Slipper Satin, the shades of which all share a subtle green undertone. This tone is particularly prominent in north-facing rooms, but is downplayed in well-lit spaces, making Old White appear as more of a grey.
 
Recommended Primer & Undercoat: Mid Tones
Complementary white: Slipper Satin