Sir Sydney is being decorated in recognition of his efforts to foster friendship between Japan and the United Kingdom and of his promotion of Japanese studies in the UK.

A Japan specialist, Sir Sydney spent 15 of his 35 years of diplomatic service in Japan. Throughout his career he promoted Japan-UK relations by raising British people's awareness of Japanese history, society and culture, and by encouraging the study of these subjects by his compatriots. Among notable events which took place during his tenure as British Ambassador to Japan between 1984 and 1986 were the decision of Nissan Motor Co. Ltd to set up a manufacturing operation in the UK and the inauguration of the UK-Japan 2000 Group. He made a particularly distinguished contribution to the Peace, Friendship and Exchange Initiative announced by then-Prime Minister Murayama in 1995, serving for eight years as Chairman of the Japan-UK Joint Committee of the UK-Japan History Project, set up to compile a history of our two countries' relations between 1600 and 2000. In addition, Sir Sydney has translated into English many works of Japanese literature and is the author of a number of books on Japan.

Together with her late husband Sir Robert Sainsbury, who transformed his father's grocery store into the famous British supermarket chain and who passed away in 2000, Lady Sainsbury made an immense contribution to the world of art, for instance through the African Art Gallery she and Sir Robert established at the British Museum. From the 1960s onwards Lady Sainsbury devoted herself to collecting Japanese works of art and did much to bring about the introduction and study of Japanese culture, centred on art and archaeology, in the United Kingdom. In particular, with Sir Robert she set up the Sainsbury Institute in Norwich in 1999, to which she added a library in 2003. Academic exchange between the Institute and Japan has flourished through the Institute's regular acceptance of research fellows from Japan and its nurturing of young researchers in Japanese art and archaeology.

One of the UK's pre-eminent scholars on modern economic history, he is particularly known in Japan as the author of The First Industrial Nation. Meanwhile, he earned the gratitude of Japan's Imperial Family by serving as supervisor to Crown Prince Naruhito while the latter was studying at Oxford University. Furthermore, Professor Mathias has distinguished himself as visiting professor at both Waseda University and Osaka Gakuin University in Japan. Since 1997 he has contributed to wide-ranging UK-Japan exchange in his capacity as Chairman of the Great Britain Sasakawa Foundation.