ok i found something on it. believe it or not, the way you pour tea in the uk is an indication of your social class
In Britain and some Commonwealth countries, the order in which the milk and the tea enter the cup is often considered an indicator of social class. Persons of working class background are supposedly more likely to add the milk first and pour the tea in afterwards, whereas persons of middle and upper class backgrounds are more likely to pour the tea in first and then add milk. This is said to be a continuing practice from a time when porcelain (the only ceramic which could withstand boiling water) was only within the purchasing range of the rich - the less wealthy had access only to poor quality earthenware, which would crack unless milk was added first in order to lower the temperature of the tea as it was poured in