Emperor Hirohito, who is posthumously known as Emperor Showa, was uneasy with Japan’s drift to war in the 1930s and 1940s but was unable to alter the course of events, according to a declassified British government assessment upon the Emperor’s death in January 1989.

Debate has often raged over the extent to which Emperor Showa was culpable for Japan’s wartime past, with some critics claiming he was complicit in the atrocities.

Writing a few weeks after the Emperor’s death, John Whitehead, Britain’s ambassador to Japan, stated, “A man of stronger personality than Hirohito might have tried more strenuously to check the growing influence of the military in Japanese politics and the drift of Japan toward war with the Western powers.

“The contemporary diary evidence suggests that Hirohito was uncomfortable with the direction of Japanese policy.

“The consensus of those who have studied the documents of the period is that Hirohito was consistent in attempting to use his personal influence to induce caution and to moderate and even obstruct the growing impetus toward war.”

But Whitehead wrote that ultimately the Emperor was “powerless” and any comparisons with Hitler are “ridiculously wide of the mark.”

Whitehead’s dispatch to the then-Foreign Secretary Geoffrey Howe was declassified on Thursday at the National Archives in London.

The Emperor was described in the letter as “ill-suited” by personality and temperament for the role of emperor.

The ambassador argues Emperor Showa did try and influence the military in an indirect way, and says one of his biggest achievements was to secure Japan’s surrender in 1945, as well as suppressing a coup in 1936.

However, Whitehead wrote there was a real possibility that if the Emperor was too insistent in his views he could have been completely isolated or replaced with a more pliant member of the royal family.

Whitehead explains that although the Emperor was considered “sacred” and all-powerful in Japan’s prewar Constitution, his power was limited by ministers and the military.

After World War II, the Emperor’s formal powers were vastly reduced and the ambassador believes the “humility” he showed was fundamental to the Japanese accepting the new constitutional framework and Allied Occupation.

He paid tribute to Emperor Showa for Japan’s international rehabilitation with his tour of European capitals in 1971.

Whitehead noted that Japanese — particularly the young — showed increased indifference toward the Emperor in the 1980s. He put this down to the Emperor’s age and the fact that he no longer played such a central role in the Constitution.