If you want Hague Blue's deep, inky teal-navy without the Farrow & Ball price tag, Dulux Viridian Tide is your best bet. It sits at ΔE 2 from the original — that's well inside the "very close" band, the kind of match most people won't clock unless they're holding the two cards side by side. Its LRV of 6.4 keeps it just as dark and brooding as Hague's own deep-end reading, so you'll get the same drama on a moody dining room or a cabinet run.
Close behind is Dulux Ink Well at ΔE 2.5, LRV 6. It's a fraction deeper and leans very slightly more navy than teal, which some people actually prefer for a study or panelled hallway. If Viridian Tide reads a touch too green for you in artificial light, Ink Well is the one to grab instead.
Here's the honest bit, though: Hague Blue's magic isn't just the colour — it's that F&B depth and the way it shifts between blue and green as the light moves. Dulux's modern emulsion finish is flatter and more plasticky than F&B's Estate Emulsion, so even a perfect colour match won't have quite the same chalky, layered quality. For a lot of jobs that genuinely doesn't matter — and the Dulux is harder-wearing and wipes down better, which is a real win in a kitchen or busy hall.
A word of warning on those ΔE figures: they're measured under controlled lighting. Hague Blue is a colour that swings hard depending on your aspect. In a north-facing room it goes properly cold and inky; in warm evening light it warms towards teal. Either Dulux match will do the same dance, so test before you commit.
Grab a sample pot of Viridian Tide, paint two coats on a bit of lining paper, and tape it up next to a Hague Blue card on the actual wall. Look at it morning and night. If it sings, you've just saved a fair bit of money.