{150}, National Theatre Wales/Theatr Genedlaethol Cymru

The brackets around {150} are ambiguous, almost apologetic. The 150th anniversary of Y Wladfa (The Colony), the semi-legendary "oasis of Welshness" in the Patagonian wilderness has given occasion in Wales for the celebration of a most unlikely story. One hundred and fifty men, women and children left their homes all over Wales and created a new life for themselves, against all the odds, at the other end of the world.

The Royal Opera Stores, a hangar-sized warehouse on an industrial park overlooked by the classic Welsh landscape of terraced housing clinging to picturesque hillsides plays host to the first-ever collaboration between Wales’ two national theatres, the English-language NTW and the Welsh-language Theatr Genedlaethol Cymru. To make matters more complicated still, the production interweaves excerpts from a forthcoming S4C film, Galesa, which also features a heavy smattering of Argentinian Spanish.

At the centre of it all is regular NTW collaborator Marc Rees, who brings his signature style of theatrical-artistic puppet-mastery to bear on what amounts to a "live documentary": visual vignettes, discomfiting soundscapes and a general mood of playful discombobulation make {150} an irreverent take on the sesquicentennial that nevertheless fails to capture head and heart all at once.

Bonneted women clutch thick black family bibles to their breasts like babies, a language and culture held to their hearts. There are cameos for Michael D Jones (Dafydd Emyr, pictured below left), the preacher whose brainchild the colony was, and for John Daniel Evans, an escapee from a band of natives who impaled his three companions, scattering their skeletons and "inserting their severed sex organs into their mouths". There are quotations from Welsh nationalist playwright and Plaid Cymru founder Saunders Lewis, a video clip of beat poet Allen Ginsberg’s "Wales Visitation, 1967" and the voice of Eluned Morgan, Y Wladfa’s de facto writer-in-residence, looms large.

There is another history at play here too. In his scripted introduction, Rees acknowledges a debt to Mike Pearson’s play Patagonia, performed at the Royal Court in the early 1990s. Brith Gof, Pearson’s company of site-specific specialists have an enduring legacy in Wales that this collaboration cements. Both NTW and Theatr Gen have become expert in staging events on a grand scale, productions which – like the story of Y Wladfa itself – become lodged in the national consciousness. But despite {150} being, truly, a significant event, its luxuriating over two and a half hours and multiple media mean there are too many lulls. Galesa seems what it is: a separate work. Sometimes less is more, and bigger isn’t always better.

The whole thing comes to life when a cast of young performers present the story of Y Wladfa at an imagined Eisteddfod, as it does when the bonneted non-Conformists inexplicably transmogrify into a weird amalgam of 21st-century hedonists and Bavarian bierkeller girls. The conceit surrounding their scattering of grain gives us a genuine, tactile connection with the unthinkably hard lives endured by the pioneers, but for the most part we remain what we are: onlookers from an altogether different time and place.

The production cannot be faulted for its ambition or the audacity of its scale. As a technical achievement {150} is stupendous; the set changes, in a venue quite literally packed to the rafters with stage equipment, are breathtaking. And after two and a half hours of promenade patchwork production, the moving final sequence that places us back in the landscape of Wales is confirmation that {150} is less about the anniversary of the colony and more about those hardy 150 souls, names listed here on packing boxes, whose echoes down the halls of history get ever louder over time. One can only wonder at what they might have made of it all.