According to the science:
Tea bag in a cup, you add milk last after leaving it at least several minutes to brew as the complex flavonoids need the heat of boiling water.
Tea leaves in a (pre-warmed) tea pot, add milk to the cup first before pouring .
Anyone who adds milk to the cup, then a tea bag and water should be taken outside and shot.
Either way, making a cup of tea isn't difficult but very few folks can make a GOOD cup of tea.
I make crap coffee but fantastic tea, or so I'm told.