Our school was without a head for a long time and the acting head was a disaster. She gave in to people for peace or popularity, created dangerous precedents and let some staff get away with totally unacceptable performance. A few things that were going on could have got us into trouble with the law or the auditors. The new head knows what needs to be done and we are 100 per cent behind him. But with OFSTED looming he hasn't a lot of time, and he is a nice person who hates telling people off or refusing them things. He says he can't risk any more ill-feeling.
I hope you have always been explicit about your support and frequently invite your headteacher to exploit it. Don't belittle his problems; even a head who is not "too nice" would not find it easy to change so much so fast, and any good manager knows that the right pace is important. A clever head can make good use of governors in these circumstances.
Encourage him to keep going and concentrate on the really bad problems. Otherwise he may upset everybody and have little to show for it. Once the staff realise his quality and his determination to rescue the school from its bad experience, they will soon forget their resentment.
You don't need to be brought in as the heavies. You can set up small groups to look at some of the areas of concern (all the easier because of OFSTED) and then the decisions will be corporate. Other problems may be better dealt with by a single governor - draw lots to be the nuisance of the month! One of our strengths is something often considered a weakness: we have "homes to go to", so being unpopular with a few teachers is not going to shipwreck us.
As some of the irregularities clearly concern the local education authority, I'm sure they will be helpful. An attached inspector, if you have one, can be a tower of strength. The imminent OFSTED inspection might also give you the excuse to buy in a consultant of some kind.
You say we must be loyal to decisions made by the governing body. What if we are sure they are wrong, perhaps illegal?
You can join a very large club! I'm not being flippant, but so many of my correspondents have this painful experience. Of course I don't think the minority are always wrong; they'll have a few saints and martyrs among them, and a large number who care about doing things properly. But it isn't enough to be right, as a governor. You have to convince others, and you may have to return to the issue another day. But sometimes you have to grin and bear it.
If you think a decision is illegal, however, you should say so at the meeting. If you can only check it later, and are confirmed in your view, you should talk to your chair. If you still aren't sure, your local governors' helpline may be able to advise you on the legal point, and if you are right perhaps suggest someone at the local authority who can intervene.