With talking to the GP and with having looked into this issue again ourselves, the emphasis will be on producing regular and predictable evacuation of the bowel by:
1. Increasing his fibre
2. Recording when accidents occur
3. Encouraging sensitivity to his body's signals that action may be imminent
4. A reward chart for clean pants
5. Possible medication if he becomes constipated (or maybe just to encourage a motion at a suitable time...certainly not an option if there are any adverse affects).
I'll write more tomorrow...I've just joined Twitter and want to get in a bit of time over there before bedtime.