Spanish White is a lovely soft off-white with that gentle warmth Edward Bulmer does so well, but it's a premium price for a premium product — natural pigments and all that. If you love the colour but not the price tag, you've got genuinely close options.
The standout is Dulux Moon Shimmer (LRV 92.3) at ΔE 0.5 from the original. That's well under 1, which means imperceptible to the human eye — you'd not spot the difference on a wall once it's up. It's the obvious choice if cost is your main driver, and Dulux is everywhere so you can grab it tomorrow.
Next is Crown Milk White (LRV 89.6) at ΔE 0.7 — also a cracking match, just a touch deeper in LRV which can read very slightly more grounded. Both are very close indeed; either will do the job.
Worth flagging COAT No Offence too. It's a much higher LRV at 99.3 and sits at ΔE 2.2 — still very close, but it's a brighter, cleaner white than Spanish White. If your room's a bit dark and you want to lift it, that brightness might actually suit you better than a literal match. COAT is also a low-VOC water-based paint with quick recoat times, so it's worth a look on its own merits.
The "but what about" here is finish and depth of colour. Edward Bulmer's natural paints have a distinctive chalky, light-absorbing quality that mass-market paints don't fully replicate — the *colour* matches, but the *character* of the surface is slightly different. If that matters to you in a feature room, it's worth a tester pot to judge in your own light.
My advice: order testers of Moon Shimmer and Milk White, paint a decent patch — A2 minimum — and live with it across a full day. Match figures get you 95% of the way; your room's light does the rest.