The good news is you don't need to pay Heritage prices to get this colour. Dulux Ashen White (LRV 71.6) comes out at ΔE 0 against Romney Wool — that's an imperceptible difference, meaning your eye genuinely cannot tell them apart on the wall. It's the same parent brand, just the standard Dulux range rather than the Heritage line, so you're paying less per tin for what is effectively the identical colour.
If you'd rather shop around, Crown Sugar Bowl (LRV 69.9) lands at ΔE 1.2 — well under the 2.5 threshold for "very close," so it'll read the same in a room. Crown is another sensibly priced trade-friendly brand, and Sugar Bowl is a touch deeper in tone, which actually helps if your room gets a lot of bright light.
For something a little softer and brighter, COAT Sweatpants sits at ΔE 1.8 with a higher LRV of 76.5. That extra lightness means it'll feel marginally airier — a sensible shout for a north-facing or smaller space where you want to bounce light around. COAT's paint is also low-VOC and washable, which is worth having if it's going somewhere that takes knocks.
Now, the "but what about" question: is the Heritage formulation worth the premium at all? Honestly, for a quiet warm off-white like this, no. The Heritage line earns its keep on deep, complex colours where pigment depth matters. On a pale neutral, the difference in body and finish is negligible — you're better off putting that saved money into a decent roller and a second coat.
My advice: order a sample pot of Ashen White and Sugar Bowl, paint two A4 patches, and look at them morning and evening before committing. With a ΔE of 0, Ashen White is the safe bet — you'll get Romney Wool for less, sorted.