Empire Grey No.171 is one of Mylands' soft, slightly green-leaning greys — the kind that reads grey in shade and shows its olive undertone when the light comes round. If you want that look in a Dulux tin, two colours get you there.
Dulux Bleached Lichen 1 (LRV 34.5) sits at ΔE 2.3 from the original. Dulux Iced Frappe (LRV 33.8) matches it at ΔE 2.3 too. Both are well under the 2.5 threshold I'd call "very close" — meaning side by side you'd see a whisper of difference, but on a wall, in a room, nobody's clocking it. The LRVs are near identical to each other, so light bounce won't differ in any meaningful way between the two.
Which to pick? Bleached Lichen 1 leans a touch greener, which is truer to what makes Empire Grey tick — that's the one I'd reach for if you specifically love the olive cast. Iced Frappe is a hair cleaner and cooler. Sample both, because at this level of closeness the deciding factor is your own light, not the numbers.
Now the honest bit: a colour match gets you the hue, not the paint. Mylands trades on depth and pigment density — their finishes have a particular richness that Dulux's standard ranges don't fully replicate, especially in a low-sheen or matt across a big wall. If the budget's tight or you're doing a rental, the Dulux match is a sensible, sound call. If this is the feature room you've been planning for months, I'd spend on the real Empire Grey and not look back.
Whatever you choose, get a proper sample pot — not a peel-and-stick — and paint two coats on lining paper. Move it round the room across a full day before you commit. A ΔE of 2.3 is genuinely tight, but your north wall at 4pm is the only opinion that matters.