Ooh, am posting for responses too. I am also looking for a good quality white to paint my interiors with (fed up of mag), a friend recommended Johnstones. Dulux are obviously the best choice but so expensive and I've got a 3 storey house so budget is important. I have always found Wilko's own paint to be pretty good, used the mag everywhere and it was really good, excellent coverage although very splattery I found. That's only £6 or 5L of white.
Farrow and Ball is such lovely paint but far more expensive than Dulux. I am using their Winterbourne White at the moment which isn't brilliant white more heading towards soft creamy old fashioned type white. Estate emulsion for an old house as water based for lime based walls.
I can recommend Dulux super matt white. It is recommended for new plaster and it is absolutely amazing, have done my whole house in it (has all been replastered). It's very similar to F&B All White which I've used previously in that it is a pure white with none of the blue of brilliant white but cheaper!
I have done a load of research on paints recently, helped by Mumsnet and various other forums frequented by decorators.
Many people recommended Dulux Trade Diamond. This is like a better version of the Dulux Easycare, which is the really tough, wipeable paint. The difference between the two comes down to opacity. The Easycare is designed for a DIY market of incompetent decorators, so it is bulked out with something called a "false body" which is basically a thickener that stops it dripping all over the place. The Trade Diamond has something called a "true body", which is a load of extra pigment that is added to increase opacity. A professional decorator should get a much better result with the latter.
You can get F&B colours mixed up in Dulux, though I'm not sure if they can do them in the Trade Diamond finish. I'm going for Jasmine White, which is similar to an F&B colour called James White. It has a greenish tinge, which picks up foliage very nicely.
Dulux trade for all my paint. I recommend it to my clients and specify it on my own house. I've got brilliant white in my kitchen and bathrooms & the kids bedrooms and it's fab, wipeable and coverage is good even in my kitchen which was dark red and DS1s room which was dark purple when we moved in (the previous owners liked strong colours - one ceiling was orange)
Yes sorry should have mentioned modern emulsion as well as estate emulsion. The modern would be better suited for the kitchen. The chalky finish is lovely on the estate one and we have had it in our sitting room for around 3/4 years now on a lime rendered wall and it is gorgeous.