When making tea add the milk first

These days we all make tea in mugs with teabags, when you have to put the milk in last.

But for those civilised people who still use a teapot, the answer to the age-old debate is that you should put the milk in first.

An old press release from the Royal Society of Chemistry explains the science behind this conclusion:

Milk should be added before the tea, because denaturation (degradation) of milk proteins is liable to occur if milk encounters temperatures above 75°C. If milk is poured into hot tea, individual drops separate from the bulk of the milk and come into contact with the high temperatures of the tea for enough time for significant denaturation to occur. This is much less likely to happen if hot water is added to the milk.

Why did this question use to occupy us so much?

This is England, so it's no surprise that the answer involves class and snobbery.

Fortnum & Mason explain:

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.