Not sure what the quality of the tea is like, but the interior courtyard of the Landmark (opposite Marylebone Station, with almost zero tourist traffic even though its only a short walk from Tussauds) is one of the most beautiful in London.

My personal problem with the Ritz is that you are there with 50 or so other groups also having afternoon tea. It just feels, well, regimented. If you REALLY want to enjoy the Ritz, then go on Sunday for Sunday lunch (exellent value set menu in possibly the loveliest dining room in town) or go for a drink in the Rivoli bar. Jacket and tie, don't forget.

And to prove you never know what you're going to get - we had tea and cake in the Orangerie canteen at Kew Gardens a fortnight ago, and it was EASILY the best cake I have had in London!