Portland Stone is one of Little Greene's quiet workhorses — a soft, greened stone neutral that sits beautifully in period and modern rooms alike. But you don't have to pay Little Greene money to get it.
The pick of the bunch is Dulux Fresh Artichoke at ΔE 1.9 from the original. Anything under 2.5 is a very close match, and 1.9 is the sort of difference you'd struggle to spot once it's dry on the wall, in normal light. Its LRV of 51 is bang in the same bracket too, so it'll bounce light the same way and read the same warmth. For a fraction of the cost, that's the one I'd reach for.
If you'd rather a different brand, COAT And Breathe comes in at ΔE 3.5 (LRV 55.8) and Crown East Village at ΔE 3.7 (LRV 55.7). Both are slightly off — a touch lighter and not quite as faithful as the Dulux — but still in the same family. COAT in particular is a cracking eco-credentialled paint with a lovely flat finish if that matters to you.
Here's the honest bit though: a colour dupe gets you the colour, not the paint. Little Greene's pigment load and depth — especially in their Intelligent Matt and Absolute Matt — is genuinely lovely and part of what you're paying for. The Dulux match will give you the *hue*, but if you're doing a feature room where finish quality really counts, the gap is more than just price.
For most jobs, mind, Fresh Artichoke in Dulux Heritage or Diamond Matt will do the business and save you a packet. Always buy a tester and brush out two coats on lining paper, move it round the room across the day before you commit — match figures are measured under standard light, and your north-facing wall doesn't care about lab conditions.