What is the standard of proof required for a deputy head to be disciplined?

76 The burden of proof is on the deputy head to establish its allegations and to establish that these allegations warrant the discipline awarded. The best articulation of the standard of proof required to meet this burden is in Faryna v. Chorny, [1951] 2 D.L.R. 354 (B.C.C.A.), para. 11: … In short, the real test of the truth of the story of a witness in such a case must be its harmony with the preponderance of the probabilities which a practical and informed person would readily recognize as reasonable in that place and in those conditions. …