If you're after a Dulux stand-in for Edward Bulmer Jonquil, you've got two strong candidates: Soft Almond 4 and Cherished Ribbon. Both sit at LRV 51.8 and both land at ΔE 2 from the original. Anything under 2.5 is a very close match — the kind of difference you'd only spot holding two wet samples side by side under harsh light, and even then you'd be squinting.
Jonquil is one of Edward Bulmer's soft, sunny yellows — that gentle, slightly chalky warmth that comes from natural pigments rather than synthetic brighteners. The Dulux matches will read the same on the wall, but worth being honest about the trade-off: Edward Bulmer's paint is made with natural earth and mineral pigments and a plant-based binder, so it has a depth and a way of shifting in changing light that mass-market emulsion doesn't fully replicate. The colour will match; the *character* under low evening light may feel very marginally flatter. For most rooms, nobody will ever clock the difference.
At LRV 51.8 this is a mid-toned colour — bright enough to lift a north-facing room without tipping into stark, soft enough not to glare in full south light. It's a forgiving yellow.
My advice: order both Soft Almond 4 and Cherished Ribbon as Dulux sample pots, paint them onto A3 boards (two coats), and live with them against your skirting and in the actual room light for a couple of days before committing. ΔE figures get you to the right pair, but your own light and the surrounding tones decide the winner. If the room's the reason you loved Jonquil in the first place — and you can stretch to it — buying the real thing for the natural-pigment depth is rarely a regret. But as a like-for-like Dulux match, either of these will do you proud.