Some people in London think the restaurant service is horrible. I find it charming.
In the states, restaurants attempt to turn over tables in an effort to bring in the maximum revenue/tips for the night. Before you can finish you dinner salad server is already bringing over your entree and likely putting in your dessert order. More often then not, the food is cooked-to-order in the states, but it sits under a heat lamp until you're finished with your first course. Your salmon might be steamy, but your mashed potatoes are luke warm. And lingering around tables after the meal will garner dirty looks from servers working on tips.
In England, however, the dining experience is much different. For starters, stay seated as long as you like. In fact, you might not even see a server pass by your table for some time. This can be somewhat problematic when you've just finished a bottle of wine and need another for the table. But in that case, you simply get up and go order one. And they don't raise their eyebrows at you for staying past desert.
I had a lovely dinner at Cafe Caldessi, and frankly all my meals in London have been enjoyable. Makes me wonder why everyone in the U.S. is in such a hurry ... sit, relax, enjoy and savor.