Shackleton left Antarctica aboard the Morning on 2 March 1903, having previously tried in vain to persuade his subordinate Charles Reginald Ford (1880-1972) to return home in his place so that he could take over his post as purser aboard the Discovery. After a short recuperation leave in New Zealand, he sailed back to England after stopovers in San Francisco and New York, arriving in June 1903. There his arrival as the first returnee of the expedition was already eagerly awaited. The Admiralty needed first-hand information to make further arrangements for the rescue of the men trapped by ice on Ross Island. With Markham's agreement, Shackleton accepted a temporary position to outfit and load the second rescue ship, the Terra Nova, but declined the offer to return to Antarctica as first officer. He took particular satisfaction, however, in the fact that an Admiralty doctor had declared him fit for duty. Instead, he helped outfit the Argentine corvette Uruguay to rescue the distressed men of the Nordenskjöld expedition.
Shackleton's attempt to obtain permanent employment in the Royal Navy failed, despite the intercession of Markham and William Huggins, president of the Royal Society.
In the autumn of 1903, Shackleton worked as a journalist and co-editor of the Royal Magazine, founded in 1898 by the publisher Sir Arthur Pearson (1866-1921), but ended this unfulfilling activity after only a few weeks. After a lecture tour on the Discovery expedition to Dundee and Aberdeen, he was offered, with the support of his friend Hugh Robert Mill (1861-1950), the recently vacant post of secretary and treasurer of the Royal Scottish Geographical Society (RSGS), which he took up on 14 January 1904. His marriage on 9 April of the same year to Emily Dorman (1868-1936), whom he had known since 1897, also brought private happiness. In February 1905 Shackleton's first son Raymond (1905-1960) was born, and in December 1906 his only daughter Cecily (1906-1957) was born.
In February 1906, Shackleton, who was completely inexperienced in business matters, got involved in a dubious speculative deal for the transport of Russian troops from Vladivostok to the Baltic Sea, which, however, did not materialize. In addition, he tried unsuccessfully to gain a foothold in politics in the 1906 House of Commons election as a Liberal Unionist candidate in Dundee. Eventually the industrialist William Beardmore made him secretary of a commission concerned with the design of new gas engines. His job was to woo Beardmore's clients and keep his professional colleagues in London and Glasgow happy.
Despite this financially secure employment, Shackleton made no secret of his ambition to return to Antarctica as leader of his own expedition. Beardmore was prepared to support him in this venture with a guarantee of £7000 (2009: €615,000). However, other investors failed to materialise for the time being. Nevertheless, Shackleton dared to present his plans to the Royal Geographical Society in February 1907. A detailed publication followed shortly afterwards in the Geographical Journal.