Amazing, I just went to my local paint shop (which shall be nameless) and discovered that they mix farrow and ball colours in johnson's paint It is £17.99 for 5 litres as opposed to about £40+ from F&B, plus their emulsion is much harder wearing than F&B
I asked and apparantly lots of Johnson's suppliers do it. Johnson's got told off for replicating the colours but F&B can't do anything about the shops that already have the codes using them.
I was about to buy a lot of it, so will save a small fortune and thought I should share it with you lot.