Not that I'd drink my tea black though. The very thought of it makes me shudder :-)
In other words, just like coffee, it's all down to personal preference. Some people can't bear the thought of adultering their lovely black tea with even a single drop of milk.
Speaking of which, I'm off to make me a coffee. With milk.
Edit: Dislcaimer - I'm not from the UK so what would I know?