What is the standard of appellate fact review in the context of an appeal?

As will be apparent from the competing submissions, the appeal is primarily concerned with matters of fact in one form or another. That prompts me to begin with a brief reference to the standard of appellate fact review. As Lensen v. Lensen, 1987 CanLII 4 (SCC), [1987] 2 S.C.R. 672; 79 N.R. 334, demonstrates, the standard is an imposing one. In the absence of "palpable and overriding error", findings of fact are not to be interfered with on appeal. The trial judge enjoys the advantage, denied us, of seeing and hearing the witnesses, and accordingly his findings, especially of primary fact, merit substantial deference.