“Faced with documentary lacunae of this nature, the judge has little choice but to fall back on considerations such as the overall plausibility of the evidence; the consistency or inconsistency of the behaviour of the witness and other individuals with the witness's version of events; supporting or adverse inferences to be drawn from other documents; and the judge's assessment of the witness's credibility, including his or her impression of how they performed in the witness box, especially when their version of events was challenged in cross-examination. Provided that the judge is alive to the dangers of honest but mistaken reconstruction of events, and factors in the passage of time when making his or her assessment of a witness by reference to those matters, in a case of that nature it will rarely be appropriate for an appellate court to second-guess that assessment.”