The Jespersen Maneouvre was a legal move for approximately three hours on the 1st of September 1993; without doubt the shortest life of any rule or amendment, in the history of the game. Aleric Jespersen was one of the team responsible for transferring the IMCS
Rulebook to computer format during the summer of 1993, and he added a bracketed subclause to Rule 38743(iii)/f:
- "Any player named Aleric Jespersen may move from any station to Mornington Crescent, at any time."
The Jespersen Maneouvre was declared void shortly after the rulebooks had been printed, but since Jespersen's IMCS membership was immediately revoked, there seemed little danger in waiting until the October update sheets before officially revoking it.