At least as old as 05-Jan-1993 17:11
Babylon 5 - (1994 show) has an interpretation of this story (season 5, cd3, its first episode)
From: dscatl!lindsay at gatech dotedu (Lindsay Cleveland)
When Bismark was Prussian Ambassador at the Court of Alexander II in the early 1860's, he looked out of a window in the Peterhof Palace and saw a sentry on duty in the middle of the lawn. He asked the Czar why the man was there. The Czar asked his aide-de-camp. The aide-de-camp did not know. The commanding general was summoned.
"General, why is that soldier stationed in that isolated place?" asked the Czar.
"I beg leave to inform your Majesty that it is in accordance with ancient custom."
"What is the origin of the custom?" put in Bismark.
"I do not recollect at present," answered the general.
"Investigate and report the result," ordered Alexander.
The investigation took three days. They found that the sentry was posted there by an order put on the books eighty years before! Records showed that one morning in the spring of 1780, Catherine the Great, who ruled Russia at the time, looked on that lawn and saw the first flower thrusting above the frozen soil. She ordered a sentry to be posted to prevent anyone from picking the flower. And in 1860 there was still a sentry on the lawn -- a memorial to habit, custom, or just everyone's saying, "But we've always done it just that way."