“The piece was originally written for female voices only (SSA) and I decided to use recurring cells of melody, but with a hidden drone of the note ‘A’ held throughout but passed from voice to voice. Most bars were repeated to create a mesmeric and chant-like effect, the short musical motifs were shared and eventually the music drifted away to a unison ‘A’ which gradually faded away to silence.
The first version has no text and was called ‘A Christmas Garland’ and is dedicated to Sarah, my wife. I knew that it would work for Double Bass, Trio and set about transcribing it a fifth lower. Now centred around D minor, with a flattened 7th, it worked beautifully for basses and I was able to add an occasional open D string to ground the piece and used harmonics to add height.
I was so pleased with the new arrangement which has already been played in Britain, America and Spain. I conducted a massed bass orchestra performance and it was a great success with many wonderful comments about the performance and the piece afterwards. It was rechristened ‘Invocation’ and I quite liked the meaning as “an incantation used to invoke a deity or the supernatural.” [David Heyes

Invocation was premiered on Sunday 13 November 2016 at Wells & Mendip Museum (Wells, Somerset) by Alex Heather, David Heyes and Jan Cowell, as part of the Wells Double Bass Academy workshop. It was also played at the Royal Northern College of Music in Manchester on the same day and received its US premiere in Los Angeles on 8 December 2016. The Spanish premiere was performed by massed basses, directed by the composer, at the Conservatorio de Culleredo (Galicia) on Sunday 19 February 2017 and the Australian premiere was in Brunswick, Melbourne on Monday 28 March 2022