(i) 重光 葵 Mamoru SHIGEMITSU http://en.wikipedia.org/wiki/Mamoru_Shigemitsu
(1887-1957; signed the instrument of surrender on Sept 2, 1945 onboard USS Missouri; Despite Shigemitsu’s well-known opposition to the war, at the insistence of the Soviet Union, he was taken into custody for war crime; convicted and incarcerated for 7 years)
(ii) 畑 俊六 Shunroku HATA http://en.wikipedia.org/wiki/Shunroku_Hata
(1879-1962; convicted for war crime, sentenced to life imprisonment, paroled in 1955)
(iii) The BBC report is correct to the extent that fourteen (14) detainees gave calligraphy to the father (named 猛男) of 高橋 昭男. However, the report is mistaken inasfar as calligraphy written shortly before execution ("执行死刑前的书法"), 14 executed, and 重光葵 and 畑俊六 executed.
(B) Indeed, the above seven were NOT those who wrote the calligraphy.
* The calligraphy was written in the summer of 1950 (昭和25年). All together fourteen detainees gave calligraphy to Takahashi's father, including, besides 重光葵 and 畑俊六, 平沼 騏一郎, 小磯 国昭, 木戸 幸一, 荒木 貞夫 and 島田 繁太郎 (all class A war criminals).
* These 14 were incarcerated in Sugamo Prison 巣鴨 拘置所 (at Tokyo), where the seven condemned had been hanged also.