Thanks Pixie, that's exactly what I thought, but was wondering if the variables of racing change the odds. Other members are always talking about working out runs of outs according to strike rates, or in this case runs of ins. Laying the 3rd fav between certain prices shows a strike rate of around 90%, and as I see it the only way to lose (I've set limits) is if 3 win in a row. So I guess that it would happen once every 343 bets or so. There's more to it than I've let on but averaging around 40 bets per day/night, it should strike the losing run once a week at worst. So with the parameters I've set , it's looking like winning 15 units x 6 days, and losing 50 units on the 7th, thus making 40 units per week.

This idea is only in its infancy but has made 76 units over 4 days/nights, and I'm dreading the losing period.