For my partner's birthday, we went to Rules, the oldest restaurant in London. We ordered the roast…read morebeef for two, and it was cooked perfectly. It came with two Yorkshire puddings, homemade horseradish, and mashed potatoes.
It was not a cheap meal, but you're paying for the ambiance, which can be described as museum-like with royal embellishments. There are so many things to look at, from James Bond's seat to the Downton Abbey section.
The service was great, and our waitress was entertaining as well as insightful. She even showed us around, pointing out the wall art and other notable items. I'd recommend coming here for a special occasion while in London, it's truly a gem of an experience.