That was before he won this year's Scottish Album Of The Year Award for 13 Lost & Found, or collaborated with Alex Kapranos, Aidan Moffat and Emma Pollock, or signed to Chemikal Underground. That was before he made a sublime new album called Breaks & Bone, inspired by The Muppets and Girls Aloud's Nicola Roberts, which includes a timely, cheering serenade called Dec 11. (Sample lyric: "I want to take my last breath by your side.")
This was in 2010, when Hubbert, a Glasgow DIY linchpin and former member of post-rockers El Hombre Trajeado, undertook a venture called Will Play For Food. In exchange for a meal, he would perform in your living room, and discuss the visceral instrumentals he had written in response to the death of his parents, his chronic depression and his divorce. It brought him to our end-terrace, where Hubbert played his debut First & Last, originally issued on his ethical label Ubisano.
Three years on, he walks back through the door, armed with a smile, a guitar and his new partner, to pick up where we left off: to play us some songs from Breaks & Bone, and charm us with his deadpan tales, in return for another cucumber-free supper.
Breaks & Bone is, says Hubbert, the concluding instalment in The Ampersand Trilogy: a triumvirate of LPs that are explicitly divergent - 2009's First & Last is entirely instrumental; 2012's 13 Lost & Found features collaborations from guest vocalists, including Kapranos, Pollock and Moffat; 2013's Breaks & Bone finds Hubbert singing his own songs.
Yet they are also implicitly linked: all were written as a way of dealing with Hubbert's depression and grief.
The records' intrinsic relationship is illustrated by Go Slowly, a gorgeous Breaks & Bone intonation, which echoes a mantra called Go Quickly from First & Last. Go Slowly is one of his earliest songs - Hubbert was playing it live four years ago - but it serves as a centrepiece on the new album, and reminds us, says Hubbert, "that I only got to make Breaks & Bone because I made First & Last".
Hubby plays Go Slowly to three of us, not counting two children pretending to sleep in their bunk beds, along with several highlights from Breaks & Bone: post-rock lullaby Bolt, the nylon-strung rave-euphoria of Buckstasy, the fret-board revelation of Tongue Tied and Tone Deaf.
The song references The Muppets, and explores Hubbert's complex relationship with his illness. "Tongue Tied… talks about how I realised that as horrible as depression is, and I would rather be without it, it has inadvertently afforded me great things," he says.
"This way of dealing with it has let me make a living from something I have wanted to do for many years. So the song is about how you can use these illnesses to motivate you to do something better; about how it is not all bad."
Its hypnotic-flamenco guitar shapes are complex, too. "Tongue Tied is extraordinarily difficult to play," he says. "It uses a technique called Alzapua, this very fast thumb triplet-strum, so you almost get a trance bassline. But it is really painful, and is really hard to pick at the same time, and then I had to learn how to put these words on top of it.
"My number one rule when I made this album was that I was never allowed to compromise the guitar playing for the sake of the words." He does not make things easy for himself.
Hubbert's exquisite musicianship was honed from years of self-teaching, but his lyric writing was, he says, almost spontaneous: the words were often penned on the day. In characteristic style, Hubbert underplays this poetic feat.
"I knew what the songs were about before I wrote the lyrics. I got the meanings in the same way I normally do - from the instrumental parts," he says.
Despite their haste, Hubbert's words are as articulate, measured and affecting as his playing - from Slights' devastating paternal farewell ("We never really spoke, but I always expected the last conversation would have some meaning"), to the love-struck turning point of Dec 11 ("tick tock, my heart stopped dead, at the sight of your smile").
There is a sense of emotional respite and healing in such lines on Breaks & Bone. Did Hubbert come up with the album title in retrospect?
"I had it reasonably early. It is a play on a Nicola Roberts song called Sticks And Stones" he says. "And my dog, D Bone, has been a constant throughout the three albums. Then I came up with this idea of drawing a line under all this, of moving on. This record is about letting go, about breaking free." He looks almost shocked at what comes next. "There's even stuff about being happy."
RM Hubbert plays the Mitchell Library, Glasgow, on January 21 with Aidan Moffat and the Cairn String Quartet, and Glasgow Royal Concert Hall on January 28 with Mogwai (both are Celtic Connections shows.) Breaks & Bone is out now on Chemikal Underground.