He studied Music and Dance at Mather College (now part of Manchester University) and is self-taught in composition.
He has led composition workshops at the Edinburgh International Festival[3] and also engaged extensively with musical activities involving the elderly and people with dementia.
[4] His piece "Hillclouds, Rainwindows and Vanishing Orchestras" has been described as "integrat[ing] tremolo sounds into a subtle patchwork of changing harmonies".
[5] He has received performances and commissions from many leading musicians, orchestras and festivals including the BBC Proms at the Royal Albert Hall,[6] London Sinfonietta,[7] Joanna MacGregor,[8] Ensemble Bash,[4] Three Strange Angels,[9] Passacaglia,[10] oboeworks,[11] Cappella Nova,[12] The Crossing,[13] Kevin Bowyer,[14] Ruth Morley,[15] and Emily Andrews.
[18] McGarr won the 2013–14 British Composer Awards (Making Music Category) for his piece Dry Stone Walls of Yorkshire, written for orchestra with soundtrack and features field recordings made on Saddleworth Moor.