THE NOTORIOUS Zinoviev letter, a mysterious document that helped destroy Britain's first Labor Party government, has re-emerged here at the center of a roaring controversy.

Historians and journalists are battling it out in that traditional arena for lofty dispute, the Times of London letters column. The issue is the same as it has been for half a century: Is the 1924 letter from Grigory Zinoviev to the minuscule British Communist Party a genuive document of conspiratorial instruction? or was the whole thing cooked up by British Intelligence, aided by a complaisant Foreign Office, to help the conservative Tories crush Prime Minister Ramsay MacDonald?

The argument was revived with the publication in a learned journal of a long article by Christopher Andrew, a Cambridge historian. After examining the admittedly fragmentary evidence, he concluded that the letter was probably genuine.

Andrew did not claim he had found any new evidence. But to believe otherwise, he argued, is to assume "a prolonged criminal conspiracy" by the British secret service and "an improbable degree of gullibility by the [civil servants] of the Foreign Office."

The unspoken implications, that that sort of thing only happens in the United States, was quickly challenged by Lewis Chester, Stephen Fay and Hugo Young. Ten years ago, working for the Sunday Times, they published an intricate account, demonstrating how the letter must have been faked. This trio gently rebuted historian Andrew observing that even senior British civil servants are not "necessarily immune from errors, particularly when the wish is such a potent father to the thought."