If you're after Wickham Gray in a Dulux tin, Clouded Pearl 1 is your best bet. It lands at ΔE 1.6 from the original, which is well inside the "very close" band — close enough that the difference is academic once it's on a wall. LRV is 69.3, so it reads as that same soft, airy pale grey-green Wickham Gray is loved for.
Runner-up is Silver Shingle at ΔE 1.7 — a whisker behind on the numbers and a touch lighter at LRV 72.9. If your room's on the dark side or you want the colour to lift a little more, Silver Shingle will throw back marginally more light. In a bright, south-facing space the two are practically interchangeable.
Why two contenders so tight together? Wickham Gray sits in that tricky pale-grey-with-a-green-whisper zone, and Dulux's lighter neutrals cluster there. The maths can't separate them meaningfully, so the deciding factor is your light, not the ΔE.
Now the honest caveat: a ΔE under 1.7 means the colours match, not the finish. Benjamin Moore's Regal Select and Aura have a depth and chalkiness to the sheen that Dulux's Diamond Matt or Heritage emulsion won't replicate exactly. If you're matching to existing Benjamin Moore woodwork or a feature wall you're keeping, that subtle finish difference can read more than the colour difference. Worth knowing before you commit.
Practical advice: don't pick from a fan deck. Order both Clouded Pearl 1 and Silver Shingle as sample pots — or better, brush a big A2 patch of each on lining paper and move it round the room at different times of day. Pale greens shift hard with light; what looks green at noon can read grey by teatime. Live with both for 48 hours and the right one will declare itself.