The whole point of neutral walls is flexibility, mate. They sit back and let your accents do the talking — so the question isn't really "what works" but "what mood do you want."
For something fresh and uplifting, bring in a soft green. Dulux Almost Pistachio (LRV 80.3) is gentle enough to read almost as a second neutral, so it's lovely on woodwork, a fireplace wall or kitchen cabinetry against beige or greige. It keeps the scheme light and airy rather than introducing a hard contrast.
If you want drama, go deep. Paint & Paper Library Blue Blood (LRV 16.4) is a proper inky blue that turns a neutral room from polite to characterful — brilliant on a panelled wall, joinery or the inside of a bookcase. The neutral keeps it from feeling oppressive, and the blue stops the neutral feeling flat. That tension is what makes a room sing.
For warmth and grounding, a rich earthy brown is the move. Mylands Cigar BH.20 (LRV 11.8) is a deep, almost smoky tobacco shade that pairs beautifully with stone and oatmeal neutrals — think a panelled lower wall, a study, or a snug. It picks up the warm undertones most neutrals carry and amplifies them.
The "but what about" question I always get: *won't accents clash if my neutral has a colour bias?* They can. Cool greige (grey-leaning neutrals) loves cool blues and crisp greens. Warm beige and stone neutrals want earthy browns, terracottas and olive greens. Check your neutral's undertone first — hold a white card next to it in daylight and you'll see whether it leans pink, green, yellow or grey.
Practical advice: pick one accent to dominate and let it repeat three times around the room — joinery, a textile, an object. Two competing accents on neutral walls usually looks indecisive. And always test accents on a board placed *against* the actual wall colour, not in isolation. The neutral changes how the accent reads, every time.