To keep the relationship firmly rooted in reality, it is critically important for the Board to immediately make certain that they have two critical components of sustainable leadership in place: a Head's Support Committee; and, a formal evaluation process. If they do not already exist (and in a surprising number of schools, they don't!), the first six months is the time to create them - before any issues arise.
Let's start with the second component - performance evaluation. Most educators are great at assessing others, but a bit resistant to being graded themselves. In actual fact, a well-conceived, professionally handled, and consistently implemented evaluation process is the best defence that a Head has against capricious criticisms and untimely dismissal. It has been my experience, that Heads are seldom let go based upon a poor evaluation result, but rather because some specific issue gets hung around their neck and no matter how well they and the school are doing otherwise, they end up being judged solely by this one measure.
The Head has little control over this happening. However, the Chair does. It is her or his responsibility to keep the Board on track and to ensure that due process is followed and that the Head is treated fairly and honourably.
There are lots of models for Head evaluation. Some just involve surveying the Board and direct reports (Assistant Head, Divisional leaders, Finance Officer, etc.) about performance and personal attributes; some use selected samples of staff or parents as well; and still others rely on a small "fact-finding" committee to interview the Head, follow up with other constituents as appropriate, and report back to the Board. In all cases, the Head should be encouraged to self-reflect; to outline her/his goals for the past year and how they have been achieved; to reiterate the Board's goals for the year and how the Head has supported them; and, to put forward the challenges and initiatives that she or he sees for the coming year.
Assessments should be annual (too much baggage can build up over time). They should be neutral (no loaded or leading questions). And, they should be confidential. This last point can sometimes be a stickler. I have seen committees who have felt that all input should be kept confidential from everyone - including the Head. This, they feel, guarantees candour. Unfortunately, all too often, it only guarantees that people can put forward their own agendas anonymously without fear of having their views contradicted.
The Committee's findings should be confidential from everyone except the Head. The Board should receive a summary report with recommendations. However, unless the report identifies a monumental concern that must be immediately addressed, the details should remain generalized. Should the committee find possible grounds for termination, then a whole new "under review" process should be initiated under the direction of a different group of trustees led by the Chair.
One way to prevent matters from getting to this point is for the Board to establish a Head's support committee. In normal times, this committee should meet regularly with the Head to hear her or his personal concerns, measure their level of stress, ensure that he or she is getting professional development, and, annually take the lead in discussions about salary and benefits. This is the group that has a "personal" relationship with the Head and so if, or when, a problem arises it can addressed here first in a safe and secure environment. Sometimes the Chair alone tries to be the support committee. This is not a good idea. It can isolate the two of them from the rest of the Board and leave the Head with only one advocate around the table when the going gets tough.
Being the Head of an independent school is a difficult job. You have to lead a complex organization; manage dozens of employees; service hundreds of clients; and keep the whole thing financially solvent. The Board of Governors has one single employee, the Head. If Boards want their schools and leadership to be sustainable over time - they have to work for it, not just keep their fingers crossed and hope for the best.