A
Roman Catholic convert, Marshall wrote stories that are usually humorous and mildly satiric and typically have religious overtones. Important themes which run through his works are
Catholicism, accounting, a
Scottish heritage and war, adventure and intrigue. Often major characters are
accountants or Catholic
priests. Characters in his novels are often fond of animals and concerned about their treatment. Contempt for modern art and literature is often expressed. Marshall's first literary work was a collection of short stories entitled
A Thief in the Night published while he was still a student at
St. Andrews University. His first novel,
This Sorry Scheme was published in 1924. A stream of novels soon followed, but none of the fiction he wrote before the
Second World War gained as much notoriety or staying power as ''
Father Malachy's Miracle'' (1931). After the Second World War Marshall became a writer full-time, giving up his work as an accountant. As to his dual career as an accountant and writer, Marshall once said, "I am an accountant who writes books. In accounting circles I am hailed as a great writer. Among novelists I am assumed to be a competent accountant." Among his better known works after the Second World War is
The White Rabbit (1953), a biography of
Wing Commander F. F. E. Yeo-Thomas, describing his exploits and sufferings as a
Special Operations Executive military adviser assigned to the
French resistance during World War II. In 1959 he was awarded the
Włodzimierz Pietrzak prize. The theme of much of Marshall's works is religion, with a focus on
Roman Catholicism. His first great success, ''Father Malachy's Miracle
, is about an innocent Scottish priest whose encounter with sinful behaviour causes him to become involved in a miracle. A number of his later novels also deal with clergy who are faced with temptation but manage to triumph in a modest and humble manner (e.g., The World, the Flesh, and Father Smith (AKA All Glorious Within
) (1944), A Thread of Scarlet (AKA Satan and Cardinal Campbell
) (1959), Father Hilary's Holiday (1965), The Month of the Falling Leaves (1963)). Other books centered on religious issues after the Second Vatican Council, dealt increasingly with the internal conflict between Traditionalist Catholicism and Modernism in the Catholic Church, such as The Bishop (1970), Peter the Second (1976), Urban the Ninth (1973) and Marx the First'' (1975). Like many
expatriates, Marshall expressed great love for his homeland. Most of his books were either set in Great Britain and/or have main characters of British nationality. The work which best shows Marshall's affection for Scotland may be
The Black Oxen (1972), which Marshall billed as a Scottish
national epic. Several of Marshall's books have themes about espionage and intrigue, such as
Luckypenny (1937),
A Girl from Lübeck (1962),
The Month of the Falling Leaves (1963),
Operation Iscariot (1974),
An Account of Capers (1988),
The Accounting (AKA
The Bank Audit) (1958), and
Only Fade Away (1954). Some of his novels feature major characters who, like Marshall himself, have suffered the loss of a limb. Often major characters from one novel appear in minor roles in other novels. Marshall was relatively popular in his time. His books were reviewed in major publications on both sides of the
Atlantic. At least two of his books were
Book of the Month Club selections;
Vespers in Vienna (1947) and
The World, the Flesh, and Father Smith (AKA
All Glorious Within) (1944), in June 1945. An
Armed Services Edition of
The World, the Flesh, and Father Smith was also produced. His books were published in at least nine languages—English, Dutch, French, German, Italian, Polish, Czech, Portuguese and Spanish. ==Film, stage and television adaptations==