In the published version of his lectures, New Theories of Everything, John D. Barrow makes reference to having delivered the Gifford Lectures at Glasgow in January 1988, but there are several references elsewhere to him delivering the Gifford Lectures in 1989 (e.g. Templeton Prize, "Fact Sheet for John D. Barrow"). In any case, "he became the youngest person to deliver the Gifford Lectures at the University of Glasgow, in the centennial year of the series." (Britannica)
New Theories of Everything: The Quest for Ultimate Explanation
In this short and rather dense book, John Barrow attempt to provide the beginnings of an answer to the question of a unified theory of everything. Breaking such a topic down into sections is both necessary and complicated, but Barrow divides the lectures into eight parts: laws of Nature, initial conditions, forces and particles, constants, broken symmetries, organizing principles, selection biases and categories of thought.