In 1972 O'Reilly composed a Celtic musical based on the Irish legend of the Children of Lir, and it premiered in Fermoy, Ireland in January 1973.

[2] The album was recorded on weekends at Trend Studios in No 10 Lad Lane, Dublin, because the musicians all had day jobs and had to travel from Fermoy.

[3] Leo O'Kelly of Tir Na N-Og produced the album, with Paul Waldron, Trend's house engineer, on the sound desk.

[3][4][6] Richard Falk wrote in the book Galactic Ramble that The Children of Lir is a "wonderful progressive folk concept album, with a mystical atmosphere and mellow vocals".

[7] Richie Unterberger at AllMusic described the album as "respectable if unexceptional folk-rock with tinges of progressive rock", and added that it has "a slightly lagging-behind-the-times feel in its basic production and earnest naïveté".