What is the legal basis for the dismissal of a master of a private school?

In Gibson v. Ross, 7 Cl. & F. 241, Lord Cottenham, L.C., at p. 254, said: Now there are many cases in which it would be highly inexpedient for the interest of a body like these trustees that a man should continue in his situation, though it might be difficult to show a legal ground for his removal. He may be unsuccessful in the discharge of his duties; he may have great abilities, but yet be unable effectually to exert them in the instruction of his pupils. This might be a great evil to an institution of this nature, and yet it might not amount to a cause which in a Court of Justice would justify the dismissal of the master. At the same time it must be admitted that the circumstance I have mentioned would form a good ground for desiring the master’s dismissal.

And Hagarty, J., commenting on the above in Weir v. Mathieson, supra, at p. 162 (3 U.C.E. & A.) says: It is needless to enlarge this list of actual, though not perhaps legal disqualifications. An unstained moral character, high intellectual attainments, and unsparing activity in the discharge of duty, may, and often do, co-exist with unhappy forms of temper, restless irritability and morbid sensitiveness, or jealousy, which may utterly unfit their possessor for the useful discharge of the delicate duties of education, and the creation of respect and confidence amongst fellow-workers and pupils.