watching Hitchcock

Saw two excellent Hitchcock pictures this week: Strangers on a Train (1951) and Dial M for Murder (1954) — each of which concerns a tennis champion with an inconvenient wife.
In the latter, Grace Kelly’s accent is sometimes plummier than her character; I wonder whether she modelled it in part on Joan Greenwood (Kind Hearts and Coronets, The Man in the White Suit, The Importance of Being Earnest).