This is a nice and slightly more up-market tea seller in London. It’s around the corner from postcard teas, so perhaps worth checking out at the same time. The East India Company were the first to import tea to England, and are still going now. They have a good selection of all types of tea, and some are available to taste. They tend to have some rarer teas, and prices are not particularly cheap, but it’s worth a look and is nice to wander around.