MacGowan has been playing improvised music since arriving from Dublin in 1990 and has collaborated with Paul Rutherford, John Stevens, Maggie Nichols, Lol Coxhill and Eddie Prévost among others. 

He helped to institute the London Improvisers Orchestra in 1998 with Steve Beresford and Evan Parker after the Butch Morris London Skyscraper tour, and also founded The Gathering with Maggie Nichols. 

In 2000 he recorded his second CD as a leader, Daybreak, with Derek Bailey, Veryan Weston, Gail Brand and Oren Marshall. Into the twenty-first century, as well as regularly playing with UK and Irish improvisers, he has also performed with Wadada Leo Smith, Greg Tate’s Burnt Sugar Arkestra, guitarists Han-earl Park and Reeves Gabrels, the Poet and Detroit legend John Sinclair, and New York based drummer Harris Eisenstadt. He has recently collaborated with drummer G Calvin Weston and has been featured on a version of John Zorn’s gamepiece Rugby which will be released by Tzadik.

MacGowan’s.. “style has the free-form panache of a Wadada Leo Smith or Joe McPhee, but his experience of other musics is never too far from the surface. Some of his gestures seem to derive from earlier forms of jazz, and there are moments of harmonic directness that you could put chord symbols under. But it has all been thoughtfully moulded into a highly convincing and distinctive language.” - Philip Clark, JazzReview