Margery Louise Allingham was born in Ealing, London.
Allingham wrote steadily through her school days, at first in Colchester and later as a boarder at the Perse School for Girls in Cambridge, where she wrote, produced, and performed in a costume play. After her return to London in 1920 she enrolled at the Regent Street Polytechnic, where she studied drama and speech training in a successful attempt to overcome a childhood stammer.
The Allinghams retained a house on Mersea Island, a few miles from Layer Breton, and here Margery Allingham found the material for her first novel, the adventure story Blackkerchief Dick (1923) which was published when she was nineteen. Two years earlier she had participated in a series of séances, during which messages ostensibly from seventeenth-century pirates and smugglers were received.
The White Cottage Mystery was her first essay in detection, written as a serial for the Daily Express in 1927 and published as a book a year later.