Dimpse is one of F&B's most useful soft greys — a cool, slightly steely mid-grey that holds its nerve in north light without going dingy. The good news is you don't need to pay F&B money to get it.
The standout dupe is Dulux Glacial Flow (LRV 65.7), which comes in at ΔE 0 from Dimpse. That's a genuinely imperceptible difference — put them side by side on a wall and you'd not call which is which. Glacial Flow in Dulux Trade Diamond Matt or Vinyl Matt will give you a tougher, wipeable finish than F&B's Estate Emulsion too, which is no bad thing in a busy room.
If you want options, Crown Sketch Pad (LRV 66.9) lands at ΔE 1.3 — still very close, just a whisker lighter and brighter. And COAT On Mute (LRV 66.8) sits at ΔE 1.7, which is well inside the "close enough" range. COAT's a nice shout if you care about low-VOC, low-faff credentials — their matt emulsion is a cracking modern formula and the colour's bang on.
The "but what about" question I always get here: *will it actually look the same on my wall?* Colour match is only half the story — the original Dimpse is famous for shifting cool in north light and warming up under lamps, and any accurate match will do exactly the same, because it's the colour doing it, not the brand. What changes between brands is the finish sheen and pigment depth, not the hue. F&B's flat emulsions have a particular chalky bloom; Dulux and Crown read very slightly cleaner. Negligible on Dimpse.
My advice: order a Glacial Flow sample pot, paint a big A2 patch, and live with it for two days across morning and evening light before you commit. If it pleases you in your room, you've just saved a tidy sum with no compromise.