There's a third pronunciation used in the motion picture “Murder by decree” from 1979: [Lestrad], ending on the same sound as in “bad” or “had”.
Sherlock Holmes (Christopher Plummer): [Reacting to the tardiness of the Prince of Wales] I suppose since, after all, he's only the Prince of Wales, we should not expect the same degree of courtesy.
Dr. John H. Watson (James Mason): And since you are the Prince of Detectives, Holmes, I don't think you should presume to criticize a man who one day will be King of England.
Sherlock Holmes: [amused] Well done, Watson! You have cut me to the quick. Hmm! Only the Prince of Detectives, you say? Then who, pray tell, is the King?
Dr. John H. Watson: Lestrade, of course.
[Holmes laughs]