From 1999 to 2006 he was a staff journalist with An Phoblacht a newspaper published by Sinn Féin, writing under the pen name Mick Derrig, a reference to Mac Giolla Bhain's maternal grand-uncle.
The book was due to be serialised in The Scottish Sun, a British tabloid newspaper, who published an article praising Mac Giolla Bhain's courage in overcoming intimidation while carrying out his work.
[9] The Sun stated that it had cancelled the serialisation because of a blog post written by Mac Giolla Bhain ridiculing Rangers fans that they considered sectarian.
[10] In 2010, Mac Giolla Bhain also broke the story of Hugh Dallas sending an e–mail which led to his sacking from the position of Head of Referee Development at the Scottish Football Association.
[19] In 2010, Mac Giolla Bhain, as a sufferer from depression, was part of a campaign by Amnesty International to raise awareness of and oppose discrimination of those with mental health conditions.