On 5 November 1942 the school was closed by the Japanese occupying army and the staff and pupils interned in an American Presbyterian mission compound on Temple Hill, Yantai.
Metcalf was a coffin bearer at Liddell's funeral in the camp in February 1945 and at the ceremony committed himself to serve as a missionary in Japan.
Metcalf arrived in Japan in November 1952 and entered the OMF International language school at Karuizawa, Honshu.
In retirement Metcalf served in ministry with the Japan Christian Fellowship, London, for a further fifteen years.
In 2005 he delivered the Eric Liddell Memorial Speech at the sixtieth anniversary of liberation of the Weishien civilian internment camp.