Here is a system that is unashamedly backfitted :

1. Same Jockey as last start
2. Last Start must have ran first or second.
3. No Resumers
4. Must have won on the track up to 3 times ( ie. won once, twice or thrice but after that they are over bet and there is no value ).
5. Unitab ratng of at least 97
6. Field size 8-12 inclusive.

Made a profit of 10% while averaging 75 bets a months and a strike rate of 26%. 12 out of 16 months were in profit over the test period.

This system could probably be slimmed down into something more useful with a higher strike rate and better POT but is not bad for a quick system.

Good Luck.