Those who like this sort of thing, wrote Abraham Lincoln, reviewing a book that he did not approve of, will find it is the sort of thing they like. Or did he? I have seen these lines quoted quite often in various shapes and sizes, but never in a form which answered the necessary questions - where did he write them, and what was the book that incurred this icy judgment? And the probable reason for that is that he probably never wrote it. If he had, someone would surely have come up with the details by now.

And that's only one of the famous things that Lincoln may never have said. Everyone knows that he said: "You may fool all the people some of the time; you can even fool some of the people all the time; but you can't fool all the people all the time." But did he? That useful internet institution Wikipedia counsels caution. These are probably, according to one of its anonymous contributors, the most famous of apocryphal lines attributed to Lincoln; yet although they are sometimes said to come from a speech he made at Clinton, Illinois, in September 1858, there is no contemporaneous record, and the quote seems first to have surfaced almost half a century later, in 1904.

And here is a later mystery, closer to home. I have quite often read that Margaret Thatcher declared that any man seen riding on a bus after the age of 30 should consider himself a failure. That most of those who have quoted this merciless sentiment have done so without checking their source is clear from the number of variants, with the qualifying age for establishing that you're one of life's losers being variously quoted as 30, 29 or even 26. Having spent much of a day trying to discover where and when she said it, I began to suspect that it might be apocryphal too.

But two versions of this superior utterance, both delivered in Commons debates, stand out from the rest. They quote her precisely, as saying: "A man who, beyond the age of 26, finds himself on a bus can count himself as a failure." More Oscar Wilde, that elegant formulation, than Thatcher, someone suggested. And I also found in the Daily Telegraph an attribution of much the same form of words to Loelia, Duchess of Westminster, a famous society snob. Could she have been the true culprit?

Then, too late in the day for me to rush off to check, I got a message from the office of one of the MPs who had used this quotation suggesting it came from a piece in the Sunday Times in November 1998. But this proved to be merely the report of what Brian Souter, chairman of Stagecoach, had recalled her as saying when he collected a business award, and seems at best to have been a casual paraphrase. So inquiries will have to continue.

So maybe she never quite said it. Maybe she has simply been pitchforked into quite a distinguished club. To judge from the list of dubious attributions on Wikipedia, Abe Lincoln must be well ahead of the field in the contest for recognition as the world's most misrepresented attributee. But he's far from alone. There is no proof at all that Voltaire ever uttered the much-quoted words, "I disapprove of what you say, but I will defend to the death your right to say it"; respectable dictionaries of quotations trace that to a book called The Friends of Voltaire by SG Tallentyre. Despite assiduous searching I have never yet seen chapter and verse for the claim that Edmund Burke once said that the only necessary condition for the triumph of evil was that good men should do nothing.

Recent thrilling Test match finishes have led writers to disinter the famous words addressed by George Hirst to Wilfred Rhodes as England closed in on victory in 1902: "Wilfred, we'll get 'em in singles." But Hirst probably never said it: some good judges assert that these words are merely what Neville Cardus thought that Hirst should have said.

Yet all of these sayings are still repeated. And that rule applies to fictional characters too. As we learned from recent obituaries of the actor who played Scotty, the captain in Star Trek who said "beam me up, Scotty" never said "beam me up, Scotty", while Sherlock Holmes never uttered his most famous judgment of all: "Elementary, my dear Watson."

What's decisive, though, is that "elementary my dear Watson" is exactly the kind of thing that Holmes might have said, which is why we tend to think it's authentic. Just as men who still travelled on buses at 26, 29 or, horror of horrors, 30, amounting to failures was exactly the sort of thing that many people suspected Margaret Thatcher might well have blurted out. Right or wrong, once these sayings get into the language they're impossible to eradicate. Elementary, my dear reader.

McElsewhere@aol.com