As actors go, Sandy Grierson is extraordinary on many levels. Not for him the workaday conveyor belt of weekly rep. This most singular of performers, currently rehearsing Little Otik, a grotesque fairy tale he's co-adapted for the stage with long-term collaborators Vanishing Point, is one of a rare breed who draw inspiration from less conventional sources. Yet, although rooted in east European mime techniques and the Polish avant-gardes, Leith-raised Grierson remains absolutely down-to-earth.

Nowhere was this more apparent than during 2007's Edinburgh Festival Fringe, when Grierson appeared in Subway, a dystopian future fantasy about a prodigal's return to a totalitarian Leith. Again produced by Vanishing Point, Subway fused a James Kelman-style interior monologue with Phillip K Dick-influenced cyber-gloom.

Acting alongside a seven-piece Kosovan band that the company stumbled upon while touring a previous show, Grierson carried Subway brilliantly as he applied his physical skills to a local demotic.

Grierson's star was already in the ascendant after taking the title role in Fergus Lamont, Communicado's adaptation of Robin Jenkins's novel. Leading an orchestrated ensemble, Grierson again relished the opportunity to combine already familiar techniques with a strong satirical narrative.

This year, following a festive turn as the Tin Man in The Wizard of Oz, Grierson displayed the full power of his talents in a solo version of The Oresteia. Onstage alone for almost an hour, he barely moved a muscle. Yet, as he delivered his lines, Grierson captivated audiences with a static display of controlled energy that left him soaked in sweat.

Such power is rare on western stages, and Little Otik is a further step up for Grierson. Taken from the 2000 film by Czech animator Jan Svankmajer, the tale of a childless couple who carve their first-born from a lump of wood is a perfect vehicle, both for Vanishing Point and Grierson.

"Various incarnations of Otik are beginning to manifest temselves," Grierson points out in a quiet basement restaurant on a break from rehearsals. "The nuts and bolts are all there. We've just got to put it together now."

In the play, Grierson plays Otik's father. This has allowed him space to be what he calls "a sounding board" for director Matthew Lenton, who has steered Vanishing Point since the start.

"The fact that we had a script to begin with is quite unusual for Vanishing Point," says Grierson. "Matt's really the adaptor, and I've been there to help. It's different from show to show how the dynamics work, and it really depends on what the project is.

Little Otik came originally from Kai Fischer, the designer. We all throw in ideas, and there was a development week, just to see if it had legs. Then the National Theatre of Scotland came on board and it snowballed from there. The point I came in at was in trying to work out how you adapt the screenplay. All the elbow grease is Matt's."

However much he plays it down, Grierson is clearly an integral part of Vanishing Point. It was part luck, part shameless blag, however, that he ended up working with the company at all.

"They needed someone to step into their show, Invisible Man, who could play violin," Grierson confesses. "I had violin playing down in my Spotlight entry, which wasn't altogether a lie, but I was pretty poor. Fortunately we had a great violin player in Ali McCrae, who was also in the show. It ended up being a great job for me, even though I was slightly underqualified. I could play a little bit, and I was practising so it wouldn't look like a complete Spotlight blag, but ultimately, in retrospect, I suppose it was. It was a very inauspicious meeting, but scraping out a tune I suppose was the beginning of forming some kind of a dynamic."

It was a dynamic that continued during the Caithness leg of the NTS launch project, Home.

Living in such close proximity, ideas were thrown up naturally, and it was during this time Grierson "jammed" the rudiments of his character in Subway.

"Things developed naturally," he says, "and that's often how the best things start."

Grierson's creative path thus far seemed fated from the start, ever since his art-student mother watched Polish wunderkind Tadeusz Kantor's Edinburgh performances in the 1970s. She took young Sandy to other Polish shows programmed for the Edinburgh Festival Fringe by Richard Demarco, who'd first brought Kantor to the capital.

"I was quite an opinionated wee ti ke," Grierson says now, "and I'd already decided what I liked, even though I didn't really have anything to compare it with. My mum took me to see Today Is My Birthday, which was the last show Kantor directed, and he died while it was being made. I remember being blown away by that, so without even realising it, you're developing this vocabulary."

While still a teenager, as well as seeing Communicado, who were probably the first Scottish company to use east European ensemble acting combined with live music, he saw Zofia Kalinska perform a one-woman show. Kalinska had been a member of Kantor's Cricot 2 company before founding her own Aerial Teatr, and invited Grierson to join a workshop. This led to performing alongside her in A Little Requiem For Kantor, and an ongoing working relationship that Grierson sees as integral to his training.

Around the same time Grierson also met David W W Johnstone, the American director of Lazzi Performance Lab. Johnstone had learned his craft from Polish actor Leonidas Durdarew-Ossetynski, and took inspir ation from Grotowski and Kantor. Grierson studied privately with Johnstone, who went on to direct Grierson in The Oresteia.

Aged 16, Grierson took a small part in Ane Satyre of the Fourth Estate, John McGrath's update of The Three Estaitis, and McGrath and his professional and life partner Elizabeth McLennan mentored Grierson further.

"They introduced a more socially aware side of things to me," he says, "so what you do is about more than just being some little aesthetic, but is about being a responsible citizen as well. A lot of Subway came from that."

Grierson never pursued a formal drama school education. This wasn't cockiness on the young actor's part. Rather, his instinctive line of inquiry had already taken him places which regular training might stifle. In this way, while Grierson is suspicious of the idea of having gurus, through his teachers he's become the youngest of a theatrical lineage.

"Both are phenomenal directors," he says of Kalinska and Johnstone, "but they're both working actors. That's been so important for me. It's almost been like being a toddler learning to walk. First, you're on a tight rein, then on the next show the reins get longer, and so it goes on."

By partly taking the reins of Little Otik, Grierson is carrying his mentors' knowledge into a modern western arena. Where he goes next he isn't sure. Ask him his ideal part, and, where other actors of his generation might look to Hollywood, Grierson, typically, goes further. "Baptiste, the mime played by Jean-Louis Barrault in Les Enfants du Paradis," he enthuses. "He put on Beckett plays and studied mime under Etienne Decroux. If it weren't for him, none of the things I'm interested in would have happened the way it did."