Born in 1975, Alastair grew up in the Shetland Isles off the North-east Coast of Scotland, UK. He studied at the Royal College of Music with Joseph Horovitz and John Birch (winning prizes in composition, organ and music history), the Guildhall School of Music and Drama with Robert Saxton and Graham Elliot, and Royal Holloway, University of London with Simon Holt where he graduated with a PhD in composition. Whilst in London, he was assistant organist at Wesley's Chapel, the Mother Church of World Methodism, and gave recitals at St. Paul's Cathedral, Westminster Abbey, Ely Cathedral, the Temple and St Brides Church, Fleet Street.

Since moving to America in 2002 to take up the position of Music Director at the Coraopolis United Methodist Church near Pittsburgh, Pennsylvania, he has given recitals through out Pennsylvania, Ohio, Georgia, New York and Iowa as well as presented workshops on new repertoire and composition. In 2007, he was invited to perform at the Morelia International Organ Festival, Mexico, where his programme of 20th century music was hailed as a highlight of the 41st festival.

He has performed and collaborated with various artists including choreographers, painters, sculptors and photographers. He is also active as a producer being involved in recording two CDs from St. Pauls Church in Akron, Ohio, and one from Waltham Abbey in Essex.
As a composer, he has written for almost every genre including an 80 minute chamber opera with a libretto by Jonathan Lennie based on the final flight of the Russian Astronaut, Vladimir Komarov. Ensembles and soloists such as the Philharmonia Orchestra, Brunel, Continuum and Composers' Ensembles, Ixion, Gilde and Belmonte Quartets, Contemporary Consort, New Noise, Scottish Chamber Ensemble, Chroma, pianist Rolf Hind and mezzo-soprano Sarah Walker have performed his work.

His work has been featured at the Spitalfields Festival, the Huddersfield Contemporary Music Festival, Norfolk and Norwich Festival, Gregynog Festival, Hoxton Music Days, all of the London Cathedrals and on London's South Bank at the Purcell Room. His music has also been broadcast on BBC Radios 3 and 4, and Radio Shetland.

Recently, he has completed commissions for the New London Children's Choir, the Rothko String Trio, the University of Pittsburgh Symphony Orchestra and violinist Roger Zahab, who performed his solo violin work A Reel Sweet Kiss in New York City and which was then broadcast on BBC Radio Scotland. His latest works, Cave Paintings for two pianos, a song-cycle: City of Passions and Poetry for soprano, piano and tape and Dragon at a Party for high voice and orchestra were all premiered in the UK and the USA to much acclaim. In 2005, he won the William Mathias Composition Competition Award and was a featured composer in the Kings Lynn Festival (UK). The groups Chroma, The Composer's Ensemble, Waltham Abbey Choir and the Pittsburgh Compline Choir have released his music on CD.

In 2004 he became Composer in Association with the Shetland Choral Society and in 2009 he was appointed Composer in Residence with the Pittsburgh Compline Choir.