Edward Bulmer is a gorgeous brand — natural pigments, plant-based, lovely depth — but it commands a premium price, and Trumpington is one of those warm, golden-mustard yellows that plenty of cheaper paints get close to.
The best value match is Dulux True Joy (LRV 48.3), which comes in at ΔE 2.4 from the original. That's well inside the "very close" band — under 2.5 means most people won't clock a difference once it's on the wall in normal light. Dulux also gives you the practical advantages: easy to get hold of, mixed at any decorator's merchant, and a fraction of the cost per litre.
Nudge over to Crown Mustard Jar (LRV 54.4) and you're at the same ΔE 2.4, but the higher LRV tells you it'll read a little lighter and brighter — more sunlit, less dirty-gold. If you want Trumpington's exact weight, go Dulux. If you fancy lifting the room slightly, Mustard Jar is the call.
The one I'd steer you away from as a straight dupe is COAT House Points — at ΔE 4.8 it's drifting noticeably off. It's a cracking colour in its own right, but it's not Trumpington. Don't buy it expecting a match.
Now the honest caveat: Edward Bulmer's natural pigments shift beautifully through the day in a way a modern synthetic match doesn't quite replicate. If that subtle living quality is *why* you fell for Trumpington, the cheaper versions will get the colour but not the soul. For a feature room you'll stare at daily, that might matter. For a hallway or a kid's room, you'll never miss it.
My advice: order a Dulux True Joy sample pot, paint a big A2 patch beside a Trumpington card, and live with it for a couple of days in your own light before you commit a full tin.