Have to admit, and this is quite the admission... my favourite tea, the one that sticks in my mind the most, was the watery hot brew of tea I had in a mess hall in Scotland. There is something about army tea... its unique... despite having a cup of tea in locations around the country and in various places in the world, its never been quite the experience of supping tea with my mates after a long night out and about.
Another tea I remember distinctly was from a butty wagon near Romford. It wasn't particularly nice tea, but it was a strong sweet tea, even without putting sugar in it.
Its weird because I'm a coffee drinker nowadays, but some of the clearest memories I have is when and where I had an unusually good cup of tea.