I assume that you are referring to staff. A verbal warning should occur after an investigation has taken place as it is a disciplinary procedure. That is assuming that it is "recorded" as a verbal warning. Your HT can, of course, speak to someone about their actions, which may or may not constitute a verbal warning. A suspension is - in theory - a neutral act which allows the school to investigate the allegations without the staff member being on site. This means that if they are serious allegations (ie placing children at risk), then the children are not placed in danger; it also means that the accuser/witnesses can feel able to speak freely and the accused cannot try to pressure them. The fact that it is a good school with outstanding behaviour is completely irrevelvant. If the person who has been accused does not agree with the warning/suspension, then that's what unions are for.