Let's be honest about what you're buying. Sanderson is a fabric and wallpaper house first, paint second — and that's the whole appeal. If you're hanging Sanderson paper or dressing a room with their fabrics, their paint is designed to sit alongside that scheme without a fight. That co-ordination is genuinely useful, and it's the main reason to reach for it.
The range itself is sensible. FiniSpec carries 154 Sanderson colours, with the strongest depth in Neutrals (27), Greys (22), Whites (22) and Blues (21), across an LRV span of 3.6 to 89.7 — so you've got everything from near-black darks to bright off-whites. The character leans English-heritage and understated rather than fashion-forward.
The colours worth knowing: Sanderson::Airlane Blue is a lovely soft mid-blue that behaves well in north-facing rooms; Sanderson::Amsterdam Green is a proper muted heritage green for a study or dining room; and Sanderson::Amanpuri Red gives you a warm characterful red without tipping into pillar-box territory.
Now the "but what about" question — is it as good as Farrow & Ball or Little Greene? Coverage, depth of pigment and finish quality are fine, but they're not in a different league. If you want the best emulsion on the market for finish and that chalky F&B depth, Little Greene's Intelligent Matt or Farrow & Ball Estate Emulsion will edge it. If you want value with strong colour, COAT or Earthborn are better shouts pound-for-pound.
My honest take: buy Sanderson when you're co-ordinating with their fabrics or wallpaper, or when you've fallen for one of their specific colours and nothing else nails it. Don't buy it expecting a step up over the heritage heavyweights — it's a good paint, not a category-killer. Always test a sample pot on the actual wall before committing, because heritage greens and blues shift hard with the light.