Bulb temperature is measured in Kelvin, and it changes paint dramatically — same wall, two bulbs, two different colours. Get this wrong and the loveliest paint job in the world looks flat.
Warm white (2700K) is what most British homes want. It throws a soft yellow-amber light, the closest electric light to a traditional incandescent or candlelight. It flatters anything warm: creamy whites, pinks, reds, terracottas and the muddy off-whites everyone loves. Farrow & Ball's Setting Plaster absolutely glows under 2700K — the same bulb that makes it sing. Slipper Satin and Pointing also come alive in warm light.
Cool white (4000K and up) is bluer and crisper, mimicking daylight. It suits cooler schemes — true greys and blues — and is genuinely useful in workspaces, kitchens and bathrooms where you want clarity. Cornforth White, Pavilion Gray and the bluer schemes hold their character under cooler light. But run a warm cream or a pink under 4000K and it'll look grey, lifeless and faintly clinical. That amber undertone gets cancelled out.
Here's the bit people miss: it's not just temperature, it's the CRI (colour rendering index). A cheap LED with a high Kelvin number and a CRI of 80 will distort colour badly. Buy bulbs rated CRI 90+ and you'll see paint as the manufacturer intended. This matters far more than chasing a specific Kelvin figure.
The "but what about daylight bulbs?" question — 5000K-6500K "daylight" LEDs are too cold and blue for living spaces. They're fine in a garage or a utility, harsh anywhere you actually relax.
Practical advice: stick to 2700K, CRI 90+ throughout living areas, hallways and bedrooms for warmth and consistency. Use 3000K-4000K in kitchens and bathrooms if you want a touch more crispness. And always test your paint sample under the actual bulbs you'll be living with — never just in daylight or under the shop's lighting.