A keen antiquarian, Higgins was a Fellow of the Society of Antiquaries. According to Ross Nichols, Higgins was also a "Chosen Chief" of the Order of Druids, founded by John Toland in 1717. Higgins was claimed a member of An Uileach Druidh Braithreaches (The Druid Order), an ancient Druid order that predates the Hermetic Order of the Golden Dawn; however, these claims are unsubstantiated. Regardless, Higgins demonstrated extensive knowledge and familiarity with the traditions of Druid orders in his work, "The Celtic Druids".