Both right -
Roald Dahl's IMDb listing
Had his own show in the late seventies (Tales of the Unexpected) and was credited with the writing (actually "story") of 7 episodes for "Alfred Hitchcock Presents" earlier in his career.
I especially remember the Gambler episode (Alfred Hitchcock Presents -
Man from the South with Peter Lorre and Steve McQueen - Episode: #5.15 - 3 January 1960 *or* Tales of the Unexpected -
Man from the South with Jose Ferrer and Michael Ontkean - Episode: #1 - March 24, 1979) where the bet was over if he could light his cigarette lighter ten times in a row without it misfiring. Good tension builing in that one.
The other one must be Alfred Hitchcock Presents -
Lamb to the Slaughter with Barbara Bel Geddes - Episode: #3.28 - 13 April 1958 AKA Tales of the Unexpected -
Lamb to the Slaughter with Susan George - Episode: #4 - April 14, 1979.
Dahl's other Alfred Hitchcock Presents episodes are -
A Dip in the Poole with Fay Wray and Keenan Wynn - Episode: #3.35 - 1 June 1958
Poison with James Donald - Episode: #4.1 - 5 October 1958
The Baby Sitter with Mary Wicke - Episode: #1.32 - 6 May 1956
Mrs. Bixby and the Colonel's Coat with Audrey Meadows - Episode: #6.1 - 27 September 1960
The Landlady with Dean Stockwell - Episode: #6.19 - 21 February 1961