It's hard to imagine two musical worlds more diametrically different than that of the late great Scottish singer and storyteller Stanley Robertson – heir to generations of traveller lore, who spent his working life filleting fish in Aberdeen – and the London glitz and fanfare of September's Mercury Prize shortlist announcement.

And yet when English folk singer Sam Lee tearfully accepted the Mercury nomination for his debut album, Ground Of Its Own, it was Robertson he thanked, having spent four years serving a highly personal apprenticeship with him, until his mentor's death in 2009.

"There's a quote from Mahler I've always loved: 'Tradition is tending the flame, not worshipping the ashes'," says Lee. "When I first heard Stanley sing, I discovered that flame was still alive."

Even before the Mercury accolade, which placed Lee in such unlikely company as Plan B, Jessie Ware, Django Django and eventual winners Alt-J, Ground Of Its Own's release in June was greeted by a swathe of glowing reviews, hailing him as a deeply authentic yet radical new voice within the current UK folk renaissance.

The authenticity comes equally from the songs themselves, most of which Lee learned first-hand in gypsy and traveller communities around Britain and Ireland – an ongoing odyssey on which he embarked after Robertson died – and from his deceptively understated, intensely eloquent singing, which fully inhabits and vividly conjures their often otherworldly narratives.

The radicalism lies in their sparse yet uncannily atmospheric – and entirely guitar-free – arrangements, gracing the vocals with delicate touches of trumpet, Jew's harp, shruti box, cello, dulcimer and tuned percussion. The CD booklet bears another favourite quote, this time from Ovid, translated as "We praise the good old times, but live today", and Lee succeeds in making music that seems to exist in both temporal realms simultaneously.

Despite his passion for and profound affinity with his material, which saw Robertson ceremonially "adopting" him as his musical next-of-kin, the 32-year-old Londoner's background makes unlikely reading for a traditional singer.

Of Polish and Jewish extraction on his father's side, he was a lonely misfit at public school who found solace in nature and the outdoors. During holidays, he attended several Forest School Camps, which drew on Quaker and Native American belief to encourage learning and self-discovery through interaction with the natural world. Crucially, the FSC organisation had its own songbook, mixing 1960s' pop and protest songs with British and American folk. "My love of folk songs does feel like a natural extension of my love for the outdoors," Lee says, "and singing at those camps definitely planted the seeds of that relationship."

However, before those seeds eventually reached fruition, he studied at Chelsea College of Art, trained as a wilderness survival teacher with Ray Mears, gained a diploma in anthropology and worked as a burlesque dancer – this last job coinciding with his initial conversion to folk music. After hearing an album by iconic English group The Watersons, the Damascene moment came when Lee traced the songs to their mostly long dead sources, via recordings of singers such as Scotland's Jeannie Robertson – Stanley's aunt – Norfolk farm labourer Harry Cox, and the Copper Family of Sussex.

"I remember when I first heard those voices," Lee says. "I remember the taste in my mouth, the smell of the room: it was one of those genuine epiphanies that makes the whole world feel different. It did make for a pretty surreal contrast with the burlesque show: every night after I'd been onstage, while I was waiting for the curtain call – still in my scanty black rubber outfit, covered in glitter – I'd sit under the dressing-room table with my headphones and notebook, completely lost in learning these ancient ballads."

However, until he met Robertson, something was missing. "I was hunting down all these songs, but it was as if I was finding all these beautiful butterflies pinned in a display case or dead in a jam jar. Hearing Stanley sing them brought them fully alive, and enabled me to bring them alive in my own way – and set me on the path of finding all these other song-carriers."

The British Isles' traveller and gypsy communities – close-knit among themselves, but outsiders from mainstream society – have long been known in folk circles as treasure-houses of tradition. For Lee, it's not only the songs themselves they preserve, but an entire pantheistic belief system enshrined in the songs, allied to a relationship with the natural world that chimes powerfully with his own.

"Some of these older singers talk very matter of factly about having visions, seeing mythical creatures, as part of their everyday experience," Lee explains. "Talking to them is like opening a window back into another world. Plants and animals have all these layers of significance – magical, symbolic, healing, spiritual – and there's a real sense of incantation about the rhythms and repetitions in some of the traveller versions of songs. Most travellers still live much closer to nature than the rest of us, and it's almost as if songs are a way for human beings to reason or negotiate with the mysteriousness and otherness of the natural world – like little ceremonies, or rituals, and in some ways singing feels like my form of prayer, too."

It's these wider and deeper contexts, or subtexts, he believes, that are often lost when learning songs from recordings – hence his latest project, the Song Collectors Collective, which he'll be launching at a day-long conference in London later this month. His hope is to inspire other modern-day enthusiasts to follow his example, in the footsteps of such illustrious forebears as Alan Lomax and Hamish Henderson, and thereby reinvigorate the first-hand oral tradition which was folk music's lifeblood until relatively recently.

"There are still a lot of song-carriers out there," he says, "and today's technology makes it so easy: while Lomax and Henderson had to haul these great heavy tape machines around, we can carry all the kit we need in a pocket – not only to record stuff, but to share it on the internet. One of my aims with the collective is to create an online, living, multi-generational archive, so that both the songs and the process of learning them from these singers are kept alive."

It may be all the time he's spent in Scotland with Robertson and his family, or perhaps his affinity with gypsy and traveller traditions, which tend to transcend national boundaries, but Lee identifies himself much less staunchly – if at all – with a specifically English folk revival than many of his contemporaries south of the border. It's noticeable, for instance, that although England is this year's international partner at Celtic Connections' Showcase Scotland weekend, an expo-style event attended by about 200 international music-industry professionals, Lee is not among the six English acts chosen to perform – a decidedly puzzling omission, given his current profile. "I applied," he says with a shrug, "but I wasn't selected."

"There's a lot of brilliant stuff happening on the English folk scene," he says elsewhere in our conversation, "but I do think there's a bit of a club mentality, a star system and a bit too much self-consciousness about the whole thing of being English – which I just didn't grow up with, being from a non-British, non-Christian family. The Scots are much better at dealing with their folk culture – there's still enough of an innate sense of identity that you don't need to cling to it in the same way, which gives you much more creative freedom. I would love to get away from the politeness and modesty that's associated with Englishness in folk music. Its original sources are such amazingly gutsy, risk-taking artists. I'd love to see a bit more sex in it."

Sam Lee plays St Andrew's in the Square, Glasgow, Friday, 7.30pm