The flaw

The flaw is that the historical results have the benefit of being able to look into the future; a powerful tool if you are trying to predict horse races!

That's why the system is at its best when the day is higher than the month. On 12th January 2009, the program looks for each horse's previous runs in races before 12/01/2009, but it receives their runs prior to 01/12/2009, including the races on 12th January!.

I've been very lucky for two reasons. I made nearly £1000 on an unprofitable system over 6 weeks with more than 1000 bets. I was also lucky to have spotted the bug on one of the days where it had any effect.

So I've gone back to the drawing board, and I think the basis of my system is still good, but nowhere near as profitable as I had previously led myself to believe.