I lived in England for two years and ate at many Chinese restaurants and never saw the dish on the menu. However, that does not mean that they didn't serve it. In the U.S. and Britain, many Chinese restaurants have two menus - one for the ethnic Chinese and one for the natives. This is because some dishes aren't received well by the British or American. They would feel awkward if some of the dishes normally served in China were seen on the menu. The Chinese restaurants naturally keep this in mind.
However, when ethnic Chinese enter the restaurant, they will many times be handed a special menu, on which you could find the dish mentioned here.
The Indian restaurants in Britain and U.S. also change their menus to suit the taste of the Westerners. Indian food served outside of India is considerably less spicy.
That is where I developed a taste for Indian food. I had always liked (Americanized) Chinese food.
Much as I loved England, I have to say that if not for the Chinese and Indian quisines, England would have no decent food to speak of. The situation may have improved while I was there, though.