But already threats of legal action from those on the suspects list are flying at Westminster. Brian Sedgemore, who was once Mr Blair's MP in Hackney, wrote to the Labour leader yesterday offering to sue "whomsoever of your aides is guilty" of mentioning his name to The Independent as the likely author of last Friday's Tribune article.
"For the record I am not Cassandra and did not write or have anything to do with writing the offending article. It lacked wit and style and its analysis was, in my view, wrong," he wrote, adding: "I look forward to seeing you as the Prime Minister for the next decade."
Cassandra predicted that Labour would win the election, but that by the end of next year a series of challenges would leave Mr Blair "isolated and weakened beyond recovery".
Tell-tale political clues in the article suggeted a member of the centrist mainstream of the party who has been an MP for some time. Michael Foot and Neil Kinnock are described as "obvious losers", while Cassandra observes of Mr Blair's leadership: "I have never known Labour MPs to be so bitterly and personally critical of their leader."
But the key political clue is Cassandra's prediction of an early "palace coup" against Mr Blair, led by Labour's own "men in grey suits", and his probable replacement by the leftish Robin Cook, the shadow Foreign Secretary who has "built the strongest parliamentary reputation since John Smith".
This is close to the known view of Ken Livingstone who wrote an article last December speculating on what would happen if Mr Blair in government tried to dismantle the welfare state: "Although Labour rules do not allow a leadership challenge while the party is in government, I have no doubt that Blair would become the first Labour leader since Gaitskell to face a serious leadership challenge if he attacked the welfare state." (Cassandra also mentioned Harold Wilson's 1961 challenge against Gaitskell.)
Intensive stylistic analysis of the article, meanwhile, reveals a tendency to long but disciplined sentences, and an unusual use of the ablative absolute.
Another suspect who has denied authorship, John Garrett, the Tribune Group member who is retiring from his Norwich South seat at the next election, was sceptical about Mr Cook displacing Mr Blair after a Labour victory: "I doubt that."
An article Mr Garrett wrote in January 1994 started with a 48-word sentence, but lacked any more conclusive evidence.Reuse content