The definition of Earl Grey Tea is simple: it's a tea (usually a black tea) with bergamot oil in it. The common myth is that the tea blend was presented to Charles, the 2nd Earl Grey by a Chinese mandarin after Charles (or one of his men) saved the life of the mandarin’s son on a trip to China. In reality, Charles never set foot in China, and the history has a more mundane beginning.
The Earl lived at Howick Hall, which had a high lime (calcium) content in its water. This gave his tea an off-flavor and he (or possibly Lady Grey, depending on who’s telling the story) consulted a tea expert for advice. This tea expert — possibly a Chinese mandarin, we don’t know — came up with the idea of adding the oil of the bergamot orange (Citrus bergamia) to the tea. This is what was served in Howick Hall, and the formula was eventually presented to Twinings by the Earl and it became one of their regular offerings.
At Red Lodge Books & Tea, we love our Earl Greys. We carry the very traditional and quite a few fun and different blends that we've developed ourselves.