Edward Bulmer makes properly lovely paint — all natural, plant and mineral based, and it earns its price tag. But if you're after that soft, chalky Portland look without the spend, you've got genuinely close options, mate.
The pick of the bunch is Dulux Heritage Linen. It lands at ΔE 1.4 from Portland, which is well inside the "very close" band — on a finished wall you'd struggle to spot the difference side by side, let alone across a room. DH Linen has an LRV of 72, so it's a light, airy off-white that holds its warmth without tipping yellow. DH is a cut above standard Dulux in terms of depth and finish, and it costs a fraction of Edward Bulmer.
If you want a closer-to-modern-paint feel with a more boutique brand, COAT Majesty's Mood is the next best at ΔE 1.6. It's a touch deeper at LRV 64.2, so it'll read slightly more grounded than Portland in a north-facing room — worth knowing if your light's already on the cool side. COAT's water-based and low-VOC, which sits closer in spirit to Edward Bulmer's eco angle.
Crown Almond Cream rounds it out at ΔE 2.1, LRV 71.7 — still well within touching distance and the most wallet-friendly of the three.
Here's the honest bit though: the thing you give up with the cheaper alternatives isn't really the colour — it's the *body*. Edward Bulmer's pigments have a particular soft, matte, almost velvety depth that natural paint does better than most. If that finish is why you fell for Portland, DH Linen gets you closest. If it's purely the colour you want at the best price, Crown will do you proud.
Buy a sample pot of all three, paint them up large, and judge them on your own walls at different times of day before you commit.