A journey through Asia Minor in 1800 to join the British fleet at Cyprus inspired him with an interest in antiquarian topography.

In 1801, after travelling across the desert with the Turkish army to Egypt, he was, on the expulsion of the French, employed in surveying the Nile valley as far as the cataracts; but having sailed with the ship engaged to convey the Elgin marbles from Athens to England, he lost all his maps and observations when the vessel foundered off Cerigo in Greece.

[3] For much of the first decade of the nineteenth century, Leake was employed by the Foreign Office to spy in Greece in the guise of a wandering tourist,[4] with the intent of gathering topographical information which would be useful in the case of a French invasion.

[5] Shortly after his arrival in England, he was sent out to survey the coast of Albania and the Morea, with the view of assisting the Turks against attacks of the French from Italy, and of this he took advantage to form a valuable collection of coins and inscriptions and to explore ancient sites.

He was also elected as a Fellow of the Royal Geographical Society, received the honorary DCL at Oxford in 1816, and was a member of the Berlin Academy of Sciences and correspondent of the Institute of France.