“It is an old maxim of mine that (мой старый принцип /расследования состоит в том, что/; maxim — афоризм, изречение; правило поведения, принцип) when you have excluded the impossible (когда исключаешь невозможное), whatever remains, however improbable, must be the truth (то, что остается, каким бы неправдоподобным оно ни казалось, является истиной). Now, I knew that it was not you who had brought it down (итак, я знал, что это не вы отдали диадему), so there only remained your niece and the maids (значит, оставались только ваша племянница и горничные). But if it were the maids (если это горничные), why should your son allow himself to be accused in their place (то ради чего вашему сыну позволять себя обвинить вместо них: «на их месте» = зачем тогда ваш сын согласился взять вину на себя)? There could be no possible reason (для этого не было возможных оснований). As he loved his cousin, however, there was an excellent explanation (однако поскольку он любит свою кузину, то появлялось великолепное объяснение) why he should retain her secret (почему он сохранил ее тайну) — the more so as the secret was a disgraceful one (тем более, что это была позорная тайна; disgrace — позор, бесчестье; унижение). When I remembered that you had seen her at that window (когда я вспомнил, что вы видели ее у окна), and how she had fainted on seeing the coronet again (и что она упала в обморок, увидев диадему снова), my conjecture became a certainty (мое предположение превратилось в уверенность).

excluded [k'sklu:dd], truth [tru:], conjecture [kn'ek]

“It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth. Now, I knew that it was not you who had brought it down, so there only remained your niece and the maids. But if it were the maids, why should your son allow himself to be accused in their place? There could be no possible reason. As he loved his cousin, however, there was an excellent explanation why he should retain her secret — the more so as the secret was a disgraceful one. When I remembered that you had seen her at that window, and how she had fainted on seeing the coronet again, my conjecture became a certainty.