Iarla Ó Lionáird sang "Casadh an tSugain" in a 2015 film based on a novel by what author?
Iarla Ó Lionáird:  He appeared in the 2015 film "Brooklyn" singing an a cappella version of the Irish folk song "Casadh an tSugain". Brooklyn (film): Brooklyn is a 2015 British-Canadian-Irish romantic drama film directed by John Crowley and written by Nick Hornby, based on Colm Tóibín's 2009 novel of the same name.
Colm Tóibín