If you love Dulux Heritage China White but want to drop into the standard Dulux range — usually cheaper, easier to colour-match at the mixing desk, and available in more finishes — Chiffon White 4 is your answer. It comes in at ΔE 0 from China White, which means the difference is genuinely imperceptible. You'd never tell them apart on a wall. Chiffon White 4 has an LRV of 85.9, so it's a properly light, bright soft white that bounces plenty of light around a room.
The runner-up is Cloudy Dreams, at ΔE 0.7 (LRV 84.2). Anything under ΔE 2.5 is what I'd call a very close match, so this is still excellent — a whisker softer and very slightly more muted. If your local stockist is out of Chiffon White, grab Cloudy Dreams without hesitation; you won't be disappointed.
Here's the honest bit, though: China White sits in the Dulux Heritage line for a reason. The Heritage emulsion has a flatter, chalkier, more characterful finish than standard Dulux, and the pigment quality reads with a touch more depth in changing light. The *colour* matches at ΔE 0, but the *paint* doesn't behave identically. If you're after that soft heritage matt look in a feature room, stay with the original. If you're painting a large area, a rental, or just want the same shade for less faff, Chiffon White 4 is the sensible move.
Whichever you go for, test it properly. China White and its matches are warm-leaning soft whites that can pull slightly different in north-facing rooms versus a sunny south aspect. Paint a sample on a couple of walls, live with it for a day or two, and check it morning and evening before you commit a full tin. Sorted.