Thank you Henry -
I have nicked the following explanation of the game off the web, but remember that you can't explain cricket to Yanks -
Mornington Crescent is a game which has baffled fans of the Radio 4 show I'm Sorry I Haven't a Clue for years. Among their frequently asked questions are "What are the rules of Mornington Crescent?", "Does Mornington Crescent have rules, and if so what are they?" and "Mornington Crescent: rules, please?". Here--at last--written by the four men in the country least likely to be able to help, is a little book which goes little or no way towards answering such queries. Naturally, The Little Book does contain an informative section on the rules of play but as these are incomprehensible to anyone who does not already know them, the section never strays from basics such as the helpful reminder that if a player moves to such a location that there are less than two occupied bases between the location played and the next but one Shift Zone, Morton's Convention being in play, whether the Loop has been vectored from either Diagonal or not... then that move is declared under-struck.
The Little Book of Mornington Crescent offers far more than mere analysis. With painstaking accuracy, the authors plot the game's history, from its origins in the Roman Empire to its present day popularity as a subject for discussion on the Internet. There are detailed discussions of key games and potted biographies of some of Mornington Crescent's most celebrated players, ranging from Mother Anna of Widdicombe to Lord Nelson. Lavishly, almost gratuitously, illustrated with black and white photographs of dubious provenance, the book includes a comprehensive glossary and even recipes for such staples as Tufnell Pork and Shepherd's Bush Pie. In fact, so informative is this book that it may be prudent to recall Jeremy Hardy's words of wisdom: "If you've understood Mornington Crescent, nothing else in your life makes sense".