
Putting the milk in first curtails the boilingnessing of the tea, and thus prevents the crackery (from which, obviously, the word 'crockery' is derived).
( ,
Tue 17 May 2011, 15:53,
archived)

and therefore "milk in first" became something only commoners did
having said that, the internet doesn't really know either, so it's all speculation
( ,
Tue 17 May 2011, 16:06,
archived)
having said that, the internet doesn't really know either, so it's all speculation