This is a bit of dispute between work colleagues. An answer would be greatly appreciated.
My argument is as follows:
If you add X amount of milk at a temperature of M to a mug at room temperature R before adding X amount of water at temp W, the result would be a cooler cup of tea than if you'd added the hot water first. This would be due to the milk reducing the overall temperature of the mug in the time that has been in it resulting in the addition of boiling water having less of an effect and resulting in a slightly cooler cup of tea/coffee.
Conversely, if you add the hot water first, due to the mug being heated, the effect of adding the cool milk will be less and therefore the end result will be a hotter cup of tea.
My Colleagues arguement is simply that it would not make a difference but without any form of justification.
If anyone can give real scientific light to this issue it would be greatly appreciated :)