He has written Doctor Who audio plays for the Big Finish range, the stage play Manhattenhenge (2008–2009) and the Rhubarb Radio series Attachment (2009). His book on Alan Plater"s The Beiderbecke Affair was published by the British Film Institute and Palgrave Macmillan on 28 September 2012. On publication of the book, he released an Author Video about the writing of it and a series of Beiderbecke podcasts: video interviews and audio commentaries for selected episodes of the Beiderbecke saga.
From 2005-2010 he wrote and presented United Kingdom Digital Video Disc Review, a podcast that peaked in the top 25 of all iTunes podcasts in all categories worldwide (British Broadcasting Corporation News reports).
He has written for publications including The Independent, The Los Angeles Times. His journalism appears in Radio Times magazine and website, plus British Broadcasting Corporation News Online.
In March 2011 he announced on his "Self Distract" blog that he was writing a four-part Doctor Who audio for Big Finish which is called Wirrn Isle. lieutenant was released in March 2012 and starred Colin Baker.
In February 2013 his third Big Finish story, Doctor Who: Spaceport Fear, was released.
The two-hour radio comedy drama stars Colin Baker as the Doctor and Bonnie Langford as Mel with guest star Ronald Pickup. A fourth, Doctor Who: Scavenger is due in March 2014. Since December of 2014, Gallagher has written app reviews and other features on MacNN.com.