Advance to Marlborough Street

No game can be quite so popular, or unappreciated, as Monopoly. After more than 60 years in the shops, it is still the best-selling board game of all, yet in the opinion of Mike Grabsky, "99 per cent of people don't know how to play Monopoly". Many of us think we know how to play, of course, but we have probably never read the rules carefully enough to appreciate the level of strategy that the game allows. In Mr Grabsky's opinion, luck plays a far smaller part than most players realise. "It's a more skilful game than backgammon," he says. There are two keys to good Monopoly: one is to comprehend the basic economics of the game; the other is to understand why it was called Monopoly in the first place.

Actually, it wasn't called Monopoly in the first place. It started life as "The Landlord's Game", invented by Elizabeth Magie and patented in 1903. She saw it, however, as not so much a game as a moral lesson against the social evils of property speculators and unscrupulous landlords. Despite her high ideas and Quaker beliefs, however, it gained a good deal of popularity and began to be played in university circles around Maryland and Pennsylvania. Over the next 30 years, the rules were gradually refined and improved. In the 1920s, it began to be known under the name "Monopoly" (despite Ms Magie's disapproval). Finally, in 1933, an unemployed engineer named Charles Darrow, who is generally credited as the game's inventor, came across it, and saw its potential. He redesigned the board, borrowed the trinkets from his wife's charm bracelet to serve as the pieces, and started marketing it properly. Omitting to mention that the game was not his own invention, he submitted it to Parker Games - who identified 52 serious faults and turned it down. Two years later, however, when Darrow had sold 5,000 copies by his own efforts, they changed their mind. By autumn 1935, Parker were making 20,000 games a week to keep up with demand.

The name of "Monopoly", however, comes from an elemnt in good strategy that few players appreciate. The complete set contains 32 green houses, and once those have been used up, no more properties may be developed until they are converted to hotels, or sold back to the bank. So one consequence is that if, for example, a player builds four houses on each of the three properties of two colour sets, it will use up 24 houses in all, leaving only eight to be fought over by the other players. You can take a large step towards bankrupting the other players by gaining a virtual monopoly over the housing market. That is why it is generally a mistake to build hotels. Four houses earn less rent, but considerably restrict the opponents' possibilities

Apart from monopolising the houses, the most important aspect of strategy is to calculate your return on investment properly. Greedy amateurs may go for the Mayfair and Park Lane set, but the economics argue against it. The pair of properties cost pounds 750, with development costs of pounds 200 a house. So to build one house on each involves a total outlay of pounds 1150, which will provide a total rent-roll of pounds 375. By contrast, the orange set, Marlborough Street, Vine Street and Bow Street, cost a total of pounds 560. For another pounds 500 you can put two houses on two of the properties and one on the other, giving a total rent roll of pounds 510.

Mayfair and Park Lane only begin to repay the investment when developed to the three-house level, and that is rarely possible early in the game. Only when the supply has been inflated by sufficient bonuses of pounds 200 for passing Go is there sufficient money in the economy to allow the development of the high-price sites.

There's another thing too that makes the orange set a good bet: because of the "Go to Jail" square, and the Chance and Community Chest cards that have the same effect, the Jail square is the one most frequently occupied. And since the majority of dice throws are in the range from five to nine, when anyone gets out of Jail he has a good chance of landing on one of the oranges.

This chance may be calculated precisely, as may other statistical aspects of the game. For example, since the average dice throw is seven, each player has a one-in-seven chance of landing on any individual square on each circuit of the board. Your expected income is therefore approximately one seventh of your total rent roll per circuit, per player. (This calculation is actually made a little more complex by the rule about having an extra turn when you throw a double, but even that may be taken into acount if you really want to do things precisely.)

The main skill at the game, however, comes not in making such calculations, but in the negotiating skills needed to tempt the other players into doing the deals that enable you to form sets in the first place. According to Mike Grabsky, each game starts with about half-an-hour of quiet play, when everyone goes round the board accumulating properties, but there comes a moment when everyone realises that progress can only be made - or one player can only be stopped - if some deals are done. Then play stops and you all start haggling. This is the vital moment and, according to Mr Grabsky, "it can get slightly nasty." It's vital not to be excluded from the deals, so sometimes you have to resort to threats. "If you don't sell me Trafalgar Square, I'll give Vine Street to Fred, and then you'll stand no chance." But the key to it all is to appear believable and trustworthy while having the mentality of a city trader.

Finally, here's another rule you've never read properly: "If a limited number of houses or hotels is left and two or more players wish to buy more than the Bank has, the Banker auctions them off to the highest bidder, starting at the lowest price shown on the relevant title deeds." Under such circumstances, houses on Mayfair and Park Lane may become a very attractive proposition. But nobody ever wins with the green set. Now go back to your constituencies and prepare to beat your kids at Monopoly.