Patchiness is one of the most common decorating gripes, and it's almost always down to one of four things: too few coats, uneven application, a porous or repaired surface drinking paint at different rates, or painting over a glossy or stained patch that the colour can't grip evenly.
The most frequent culprit is fresh plaster or filler that wasn't sealed. New plaster sucks moisture out of paint unevenly, leaving dull, blotchy areas. Always give bare plaster a mist coat first — emulsion thinned roughly 70:30 with water — then two full topcoats. Patch repairs (filler over old paint) create the same problem: the filled spots flash matt while the rest stays sheen. Spot-prime repairs with a coat of the topcoat before doing the full wall.
If the wall was sound but it's still patchy, you've likely stretched the paint too thin or worked it for too long. Cheap trade emulsions and deeply pigmented colours are the worst offenders — strong reds, yellows and dark blues like Farrow & Ball Hague Blue or Stiffkey Blue often need three coats for solid coverage, sometimes over a tinted primer. Don't fight it; build the coats.
Application matters too. Use a decent medium-pile microfibre roller, keep a wet edge, and lay off in one direction so you're not leaving roller tracks and overlaps that read as patches once dry. Don't go back over half-dry paint — that drags the surface and causes flashing.
For a reliable, forgiving finish I'd reach for Little Greene Intelligent Matt or Dulux Heritage — both flow well and level nicely. If you want something that buries previous patchiness, Crown's higher-opacity trade emulsions cover honestly in two coats. For chalky, breathable walls, Earthborn Claypaint hides unevenness beautifully but does want a stabilised surface underneath.
Practical fix for a wall that's already patchy: let it cure fully, lightly abrade any sheen with a fine pad, spot-prime repairs, then apply two even topcoats across the whole wall corner to corner. Don't patch-paint over patches — it never blends. Sorted.