Extras they might be, but make no mistake: there is nothing extraneous on this album. As with RM Hubbert's exquisite guitar instrumentals; as with his devastating songs and warm collaborations – as with the three albums that preceded, and engendered, this long-player – Ampersand Extras is a masterclass in musical economy.

It is also a vital adjunct to what Glasgow flamenco-punk guitarist Hubbert has termed his Ampersand Trilogy: a triptych of diverse yet intimately related albums that explore, and deal with, love and loss – from 2009's instrumental First & Last, through 2012's collaborative Scottish Album of the Year Award-winning 13 Lost & Found, to 2013's Breaks & Bone, which saw him finally find the words he wanted to say, and the voice to sing them.

Ampersand Extras excavates and recontextualises previously unreleased works and tour-only rarities from the Ampersand Trilogy's recording period. In doing so, it brings the albums closer together, while offering a final chapter, and meditation, on one of the most prolific and critical bodies of work in contemporary Scottish music.

Hubbert started to make solo music in the mid-late 2000s, largely as a way of processing and articulating his grief for the loss of his parents; the break-up of his marriage; his clinical depression; his regrets and memories; his love for his family, friends and legendary dog, D Bone.

D Bone is one of several recurring stars that make a welcome return on Ampersand Extras, on 'For Fuck Sake D, Sit Nice', and several familiar characters make a (re)appearance – Emma Pollock, Alasdair Roberts, Luke Sutherland and former El Hombre Trajeado comrade Stevie Jones (well, his baby) among them.

When Hubbert released Breaks & Bone, he said he was seeking to move on from the Ampersand Trilogy's commemorations and songs. Ampersand Extras sets him free. It embraces and entwines itself around the loose ends; upturns the few remaining stones; and provides an evocative, beautiful means of drawing a line in the (amper)sand.