It's a good obit, but it doesn't mention Allyson's finest (at least to me) role, as librarian Connie Lane teaching Peter Lawford's Tommy Marlowe a little French in Charles Walter's fine 1947 musical Good News.
Lawford spoke French, Allyson didn't, so he taught her how to instruct him in "The French Lesson" scene, which with its half-spoken song predates Rex Harrison's singing style in My Fair Lady by almost ten years.
Allyson wasn't drop-dead beautiful, nor did she project a particularly strong personality onscreen; she was more wholesome and lighthearted than anything (though she did show a dark side in The Shrike (1955) and They Only Kill Their Masters (1972)). By her own admission couldn't sing or dance either, but that didn't stop her from being enchanting when, after "The French Lesson" number she sings "The Best Things in Life are Free." The pure yearning and passion there transcends any suggestion of wholesomeness that might weigh her down (or at least render the issue irrelevant); she fully justifies Lawford's smitten delivery of the lines (spoken as he gazes at her eyes) "they sure are blue."