Here you go(c/o Fortnum and Mason):
This thorny question has divided tea drinkers for quite some time. Putting the milk in last was considered to be the ‘correct’ thing to do in refined social circles, but the reason for this is often forgotten. In the early days of tea-drinking, poor-quality cups were inclined to crack when hot tea was poured into them, and putting the milk in first helped to prevent this. When finer and stronger materials came into use, this was no longer necessary – so putting the milk in last became a way of showing that one had the finest china on one’s table. Evelyn Waugh once recorded a friend using the phrase ‘rather milk-in-first’ to refer to a lower-class person, and the habit became a social divider that had little to do with the taste of the tea.
Having said that, there is a good reason for adding the milk last – if you are drinking an unfamiliar tea, it is easier to judge the correct amount of milk to add once you have seen the strength and colour of the tea. On the other hand, putting the milk in first means that the fat in the milk emulsifies in a different way when the tea is poured, which does change the flavour of the tea, giving it a more even, creamier flavour. It also cools the tea slightly to a more acceptable drinking temperature. So, now that the days when one’s social position was judged by this sort of thing are long gone, you may pour your tea however you choose.
So it depends if you are a snob and/or lack confidence with your tea or if you prefer a creamer brew.
Well I never.