In the two positions we have discussed so far a gammon was out of the question. When there is a chance of a gammon the whole situation is completely changed. If you accept a double from 1 to 2 and then lose a gammon, your decision to accept the double has cost you an additional three points because you have lost four instead of one. That's a very different matter from the additional one point it costs if you merely lose a single game. Suppose you were doubled in a situation where your downside risk was a gammon, but you only stood to win a single game; and suppose you had a 50 per cent chance of winning. If you rejected the double, then you would lose two points in two games. If you accepted the double, you would lose four points once and win two points once. So on balance you would come out the same, having lost two points. No better and no worse than refusing the double. Without the danger of the gammon it would have been the most obvious of takes. Of course, in practice you don't get such a straightforward Situation. Normally there is quite a chance that, although you may lose a gammon, you may lose only a single game. A good rule of thumb in these cases is: if you think that you have at least as good a chance of winning the game as of losing a gammon, then take the double. Otherwise drop it.
In the section before on doubles offered towards the end of the game, the message was that you should be inclined to accept doubles even though the odds were against you. You can't lose a double game and, on balance, you lose less by accepting the doubles unless your chance is below one in four. But here in the middle game the general message for the average player is that he should be very cautious about accepting doubles. All too often the beginner sees that the situation is one where things could well turn round. He forgets that things can also get a lot worse so that he loses a gammon. There is no golden rule which teils you whether you are more likely to win a single game or lose a double. But all the same, it s a good way of looking at the problem because, with experience, you will come to have a much better feel for which is the more likely. I am going to give you some examples of common situations and teil you what to do. This will obviously help you when these situations come up. It will also teach you how to think about other positions.