You've heard of False Memory Syndrome. But what of False Rumour Syndrome, the disease that last week impelled Ronan Keating to deny publicly rumours that his wife had found him in bed with a male rock singer?

Ronan and Yvonne are not the only victims of untrue rumours. Take our first President, Douglas Hyde. He faced rumours in 1943 that he was senile and a sexual predator who chased women around the Aras in his wheelchair.

Myles na Gopaleen even wrote a limerick about Hyde's "sex-life" while "senility" was mentioned in the Dail. Yet not a word of it was true.

President Hillery faced a similar farce in 1979 when, on the eve of the Pope's visit, Dublin became awash with rumours regarding his marriage. For days, L'Affaire Hillery was supposed to be about to break in Belgium's Le Soir newspaper or Ireland's Hibernia magazine. But it too was complete fiction, as Hillery revealed once the Pope had left the country.

Popes too have been the victims of innuendo. In the 1950s Pope Pius XII's "relationship" with his German nun housekeeper was gossiped about, but a far more widespread rumour concerned Pope Paul VI. The far-right wing of the French press (which hated him because he was considered too liberal), claimed the first thing he did once elected was send his homosexual priest-lover to a parish far from Rome and out of the reach of nosey journalists.

To kill what Pope Paul called the "scandalous rumours" he told crowds at a general papal audience: "We are not homosexual." But the rumours persisted. When, years later, it was discovered that mafia types had infiltrated various church-owned or -linked Italian banks, the rumour was that they were blackmailing the Pope to look the other way.

For classic rumours one need look no further than British royalty. Did you know, for example, that Queen Victoria secretly married her servant John Brown and had his love child, who then lived to a great age in Paris?

Victoria and Brown may have been lovers; her children suspected it. And she did have mementoes of Brown put into the coffin with her. But marriage? Unlikely. And a love child? Biologically impossible. She was in her 50s when they met.

Then there is the story that one of her grandsons was Jack the Ripper. The Duke of Clarence did have a controversial sex life, being caught up in the Cleveland Street gay brothel scandal in the 1890s (or would have been if the government had not covered it up).

But he could not have been Jack the Ripper for the simple reason that he was not in London when the murderer struck, on one famous occasion being in Balmoral in view of Queen Victoria, Gladstone, the Home Secretary and 100 servants.

His younger brother, as King George V, was once accused of polygamy, married simultaneously to Queen Mary, an admiral's daughter in Malta and a Cork woman, with whom he supposedly had three children. In 1911 he sued the journalist spreading the stories for libel and won.

As for the present British Queen Mother, rumour has it that she is one of a set of twins born in Waterford and adopted by her Scottish family.

But I kept the oddest one to last. Maggie Thatcher was not the first Tory prime minister to wear a dress, you know; that was Harold Macmillan, a closet transvestite. JFK heard that one and asked did Macmillan and the Queen share the same dress designer.

So cheer up, Ronan, the latest victim of False Rumour Syndrome. Kings, popes, presidents and queens of all sorts have been there before you. And after all, having killed one rumour, you will have at least a month before the next one starts.