Your best bet is Dulux True Joy (LRV 48.3), which lands at ΔE 2.4 from Edward Bulmer Trumpington. Anything under 2.5 is considered very close — the difference is there if you put the two side by side under harsh light, but on a wall you'd struggle to tell them apart.
The next option is Dulux Honey Mustard (LRV 47.9) at ΔE 2.9. That's a touch further off — perceptible if you're really scrutinising — but still a fair shout if True Joy isn't doing it for you in the room. Notice both Dulux candidates sit at almost identical LRVs (48.3 and 47.9), so neither will throw your light levels off relative to the original. That's reassuring: you're matching the depth as well as the hue.
Now, the honest bit. Trumpington is one of Edward Bulmer's natural-pigment colours, and a lot of what makes those paints special is the way the pigments shift through the day — that gentle, alive quality you don't quite get from a standard mineral-and-synthetic Dulux mix. A ΔE 2.4 match nails the colour at a single moment, but it won't replicate that depth of movement. If the reason you fell for Trumpington was its character, the match will feel a little flatter, even though the figures are tight.
So: if you want the colour for budget, availability, or because you're already buying Dulux for the rest of the job, True Joy is the one to order. Get a tester pot and paint a decent patch — at least an A4 swathe — then live with it against the original swatch for a couple of days before you commit.
And if it's genuinely Trumpington you've fallen for, spend the extra and buy the real thing. A ΔE of 2.4 is close, but it's not the same paint.