Visiting Chinese President (2nd L, front), his wife Peng Liyuan (2nd R, front), British Queen Elizabeth II (1st L, front), and Prince Philip (1st R, front) attend a traditional ceremonial welcome in London, capital of Britain, Oct. 20, 2015. (Xinhua/Pang Xinglei)

Visiting Chinese President Xi Jinping attends a traditional ceremonial welcome held by British Queen Elizabeth II in London, capital of Britain, Oct. 20, 2015. (Xinhua/Rao Aimin)

Chinese President Xi Jinping and British Queen Elizabeth II ride a carriage to Buckingham Palace in London, Britain, Oct. 20, 2015. Xi attended a traditional ceremonial welcome held by the Queen at the Horse Guards Parade in London on Tuesday. (Xinhua/Rao Aimin)

Chinese President Xi Jinping and his wife Peng Liyuan, accompanied by British Queen Elizabeth II and Prince Philip, ride carriages to Buckingham Palace in London, Britain, Oct. 20, 2015. Xi attended a traditional ceremonial welcome held by the Queen at the Horse Guards Parade in London on Tuesday. (Xinhua/Zhou Lei)

Chinese President Xi Jinping and British Queen Elizabeth II ride a carriage to Buckingham Palace in London, Britain, Oct. 20, 2015. Xi attended a traditional ceremonial welcome held by the Queen at the Horse Guards Parade in London on Tuesday.(Xinhua/Zhang Duo)

Chinese President Xi Jinping and British Queen Elizabeth II ride a carriage to Buckingham Palace in London, Britain, Oct. 20, 2015. Xi attended a traditional ceremonial welcome held by the Queen at the Horse Guards Parade in London on Tuesday. (Xinhua/Zhou Lei)

Chinese President Xi Jinping and British Queen Elizabeth II ride a carriage to Buckingham Palace in London, Britain, Oct. 20, 2015. Xi attended a traditional ceremonial welcome held by the Queen at the Horse Guards Parade in London on Tuesday. (Xinhua/Zhang Duo)

Chinese President Xi Jinping, accompanied by Prince Philip, inspects the guard of honor during a traditional ceremonial welcome held by British Queen Elizabeth II at the Horse Guards Parade in London, Britain, Oct. 20, 2015. (Xinhua/Pang Xinglei)

Chinese President Xi Jinping, accompanied by Prince Philip, inspects the guard of honor during a traditional ceremonial welcome held by British Queen Elizabeth II at the Horse Guards Parade in London, Britain, Oct. 20, 2015. (Xinhua/Rao Aimin)

Chinese President Xi Jinping (C), accompanied by Prince Philip (R, front), inspects the guard of honor during a traditional ceremonial welcome held by British Queen Elizabeth II at the Horse Guards Parade in London, Britain, Oct. 20, 2015. (Xinhua/Pang Xinglei) 10

A traditional ceremonial welcome held by British Queen Elizabeth II for visiting Chinese President Xi Jinping is held at the Horse Guards Parade in London, Britain, Oct. 20, 2015. (Xinhua/Rao Aimin) 11

Chinese President Xi Jinping and his wife Peng Liyuan, accompanied by British Queen Elizabeth II and Prince Philip, ride carriages to Buckingham Palace in London, Britain, Oct. 20, 2015. Xi attended a traditional ceremonial welcome held by the Queen at the Horse Guards Parade in London on Tuesday. (Xinhua/Pang Xinglei) 12

Chinese President Xi Jinping and his wife Peng Liyuan, accompanied by British Queen Elizabeth II and Prince Philip, ride carriages to Buckingham Palace in London, Britain, Oct. 20, 2015. Xi attended a traditional ceremonial welcome held by the Queen at the Horse Guards Parade in London on Tuesday. (Xinhua/Zhou Lei) 13

Chinese President Xi Jinping and British Queen Elizabeth II ride a carriage to Buckingham Palace in London, Britain, Oct. 20, 2015. Xi attended a traditional ceremonial welcome held by the Queen at the Horse Guards Parade in London on Tuesday. (Xinhua/Rao Aimin) 14

Chinese President Xi Jinping and his wife Peng Liyuan, accompanied by British Queen Elizabeth II and Prince Philip, ride carriages to Buckingham Palace in London, Britain, Oct. 20, 2015. Xi attended a traditional ceremonial welcome held by the Queen at the Horse Guards Parade in London on Tuesday. (Xinhua/Zhou Lei) 15

Chinese President Xi Jinping and British Queen Elizabeth II ride a carriage to Buckingham Palace in London, Britain, Oct. 20, 2015. Xi attended a traditional ceremonial welcome held by the Queen at the Horse Guards Parade in London on Tuesday.(Xinhua/Zhang Duo) 16