1948 also saw the publication of Lethbridge's first major book, "Merlin's Island: Essays on Britain in the Dark Ages", a collection of six essays on various elements of Early Medieval Britain. Representing Lethbridge's unorthodox and eclectic approach, it was aimed at a popular rather than academic audience, and although some academic reviewers were critical, it received much qualified praise. This was followed in 1950 by "Herdsman and Hermits: Celtic Seafarers in the Northern Sea", in which he returned to his interest in seafaring and boats. Containing a foreword by Kendrick, it was published by Bowes and Bowes. In 1952, Lethbridge published "Coast Wise Craft", which again looked at boat building but was aimed at a general rather than specialist readership. That same year, Thames and Hudson published Lethbridge's "Boats and Boatmen" as part of their "The Past in the Present" series edited by archaeologist Jacquetta Hawkes. In 1954, Andrew Melrose published Lethbridge's "The Painted Men", a book about the Picts of Northern Britain. It was deemed to be his last conventional book within the archaeological and academic community. As part of his increasing public profile, the BBC invited him to give the third talk in their second series of "Myth or Legend?", which he devoted to the question of whether Europeans had arrived in the Americas prior to Christopher Columbus; in particular he looked at the claims that St. Brendan and Thorfinn Karlsefni had made the journey across the Atlantic. Over several seasons he also carried out excavations of wheelhouses at South Uist, and on one occasion was visited at the site by Queen Elizabeth II and Prince Philip, Duke of Edinburgh.