Edward Bulmer's Spanish White is a cool, chalky off-white, and the trick to making it sing is to keep everything around it in the same cool, slightly greyed family. Lean into soft greyed greens and pale stone, and choose polished nickel for taps and handles rather than brass — warm metals fight the temperature of this colour.
For a partnering green, Mylands Artichoke BH.13 (LRV 27.6) is the one I'd reach for. It's a muted, dusty green that sits comfortably against Spanish White without ever feeling jarring — proper soft sage territory, ideal for a feature wall, panelling or joinery in a room where the walls stay pale.
Want a touch of depth and drama? Dulux Sapphire Springs 1 (LRV 6.4) is a deep, near-inky blue that works beautifully as an accent — a chimney breast, a back wall in an alcove, or the inside of bookshelves. At that LRV it's properly dark, so use it where you want contrast rather than over a whole room.
For woodwork and trim, Paint & Paper Library Slate IV (LRV 67.5) is the move. It's a pale, soft stone-grey that gives you definition against the Spanish White without breaking the cool palette. That's exactly the pale-stone-for-woodwork strategy that suits this colour — quiet, considered, and it lets the green and blue do the talking.
The one thing to avoid: don't reach for a warmer cream or a magnolia-ish off-white as a companion. The moment you put a yellow-based cream next to Spanish White, the white reads grey and dull rather than chalky and fresh. Keep your whole scheme on the cool side of the line and you'll get that elegant, slightly Scandinavian calm this colour does so well.
Practical tip: sample Spanish White against both north and south light before committing — cool whites shift more than you'd expect, and you want to be sure the greyed greens still feel soft rather than flat in your particular room.