After a brief spell with the Rand Daily Mail, which ended after an argument with the proprietor, Wallace returned to London and resumed his association with the Daily Mail, as a day-today reporter. By this time Wallace was heavily in debt after gambling on the South African Stock Market and also starting to lead the extravagant lifestyle to which it was clear he wished to become accustomed. Money troubles led him to commence work on his first full novel; The Four Just Men.

However, instead of proceeding conventionally, Wallace decided to embark upon a scheme which he believed would earn him a lot more. In 1905 he founded the Tallis Press, his own publishing company and decided upon a grandiose marketing and publicity campaign. Central to this was a competition he ran which invited readers to guess the solution to a conundrum – namely how the ‘Foreign Secretary’ had been murdered by ‘anarchists’ in the storyline. Extravagant prizes were offered by Wallace, to whom it never occurred that more than one person might win. He also underestimated production and publicity costs. Sinking even deeper into debt, he was bailed out by a large loan from Alfred Harmworth, the proprietor of the Daily Mail, who was concerned the bad publicity surrounding the events would harm the newspaper.

There then followed two libel actions involving the Mail in which Wallace was concerned – one of his own making after he had made up part of a story, and one involving a campaign Harmsworth was running against the soap manufacturers, Lever Bros. In the event, he was dismissed from the paper in 1907 and his standing in Fleet Street was so low no paper would employ him. By this time Ivy had given birth to a second surviving child, a daughter, and Wallace was effectively bankrupt, albeit not declared as such.

In 1909 he hit upon the idea of using some of his knowledge from reporting for the Mail in the Belgian Congo was as a basis for a series of short stories for a penny magazine. The initial batch, which were full of adventures of empire, a little patronising of native Africans, and contained strong characters, were a huge success and were eventually published in 1911 as Sanders of the River, the first of eleven such volumes.

Journalistic employment once again followed and Wallace also indulged in one of his great passions; horse racing. He both gambled and wrote about the subject and became tipster for various papers prior to starting two of his own. Another child was born to Ivy in 1916, but their marriage was failing and they were divorced in 1919. Shortly afterwards, Wallace married the daughter of a financier, Violet King, who had previously been one of his secretaries. They had a child, Penelope, in 1923. During the first World War Wallace had also served as a Special Constable at Lincoln’s Inn and as a special interrogator for the War Office.