English sign 'Trespassers will be prosecuted' is an exageration

Another illusion shattered - and a gap yawning in English law.

For generations, Englishmen have quailed and turned back from fields, woods, and property at the sight of those legendary notices dotting the English countryside, ''Trespassers will be prosecuted.'' But, it now appears, they are not only highly misleading but hardly have any teeth at all.

In A. A. Milne's Winnie the Pooh stories, Piglet had one of the signs outside his forest home. True, it had weathered to the point where it read only ''Trespassers W'' and Piglet solemnly explained that it referred to his uncle, ''Trespassers William.'' But the implied sternness was there.

Today - after the recent and almost unbelievable entry of Michael Fagan, unemployed father of four, into Buckingham Palace and into the very bedroom of Queen Elizabeth II herself - the spotlight has been turned on the stern warning anew . . . and revealed it to be illusion.

People were startled to discover that Mr. Fagan could not be prosecuted for a criminal offense because of his trespass into the most famous home in the land.

''Under British law,'' a solicitor (lawyer) explained to the Monitor in an interview, ''trespass is only criminal if there is an intent to commit a criminal offense - for instance, if the intruder is armed, or breaks something to get in, or steals something, or otherwise causes damage.''

Mr. Fagan climbed into the palace through a window carelessly left open. He broke nothing. He was not armed. He hurt no one, but only talked to the Queen for 10 minutes before Her Majesty summoned a footman and had him removed.

Among other things, he told the astonished monarch that security at the palace was ''diabolical'' - by which he meant poor - and that she should do something about it. (Fagan has since been charged with three other offenses - stealing a half bottle of wine from the palace on an earlier entry June 7, stealing a car June 16, and assaulting his teenage stepson June 26.)

The Queen could bring a civil suit against Mr. Fagan for assault and battery, claiming she had been rendered afraid and upset by his sudden appearance in her bedroom. She would have to claim monetary damages.

She will not, however, engage in any such thing. Her evidence would be required. It is just not done.

Lawyers here agree that there is a gap in the law. '' 'The trespassers will be prosecuted sign' is misleading,'' the lawyer contacted by this newspaper said , ''because it gives the impression that you will be criminally prosecuted.''

''In fact, you cannot be. The farmer or property owner can take you to court, but if you hadn't done any damage, all he would be awarded would be one penny in damages. If you offered him (STR)5 before the proceedings and he refused, the court would order him to pay his own costs and yours. In fact, no one would sue you for trespass under ordinary circumstances.''

Former president of the Law Society, Sir David Napley, says the law should be changed. Trespass should be criminal if carried out into a dwelling ''under circumstances likely to occasion harm, alarm, or embarrassment.'' The lawyer I talked to said, ''I entirely agree.''