The French Connection
Every good Briton knows that adding milk to the pot (or even worse, to a tea-bagged mug) lowers the water temperature which prevents release of all the mystical goodness locked in the tea leaves.
The French, on the other hand, believe tea should be made with lukewarm water. After too many putrid experiences with "le cuppa", I now take my own travel kettle with me when venturing onto the continent.
I would launch an urgent HR investigation into said staff member - s/he may be harbouring secret Francophile sympathies, in which case they should immediately be stripped of tea-making duties - and put in charge of lunch.