PICTURE the scene: in the same cheerily informal space, littered with café tables, you can see one of William S. Burroughs’s pieces of shotgun art, a huge hanging from West Africa made of liquor-bottle tops and copper wire, and a bright abstract from Ghana. Over there is a delicately silvered piece from China that looks like a screen in four panels and a blobs-and-bars abstraction by Aubrey Williams from Guyana. And here’s a labyrinthine red-on-red painting by Gerald Wilde entitled Intelligence Now!, from which the exhibition takes its name.

So where are you? There could, in London at least, be only one answer to that. You must be in the October Gallery. The names of Gerald Wilde and William S. Burroughs offer an immediate clue, since both are artists primarily associated with the gallery, and the selection of other, what for want of a better term we might call ethnic, art clinches the matter. For the past 25 years the gallery has offered a variety of unfamiliar art that nowhere in this country begins to match.

How on earth has it managed, given that it is a commercial gallery that depends in large measure on sales for its continuing existence? There are some unseen assets. The building on the fringes of the West End comes at a peppercorn rent, so that some income can be made from hiring out its various subsidiary spaces. In early days it attracted the interest of an eclectic collection of art-world grandees such as Sir Roland Penrose, Tambimuttu, Lawrence Durrell, Ronnie Scott and Burroughs.

All of these were invaluable for attracting attention and forging contacts. But the most important element through the years has been the dedication (they laugh if you say fanaticism, but it still has an element of truth) of the director Chili Hawes and artistic director Elisabeth Lalouschek, aided and abetted by Kathelin Gray and Gerard Houghton, in charge of special projects.

And what are they fanatical about? Well, the label when the gallery opened in 1979 was “Artists from around the World: Intelligence, Intuition and Action”. Nowadays they say “the Ecology of Art”.

Of course it takes more than dedication, or even fanaticism, to run a gallery for a quarter of a century, particularly one that needs to succeed to some degree commercially, It certainly takes all the intelligence, intuition and action that can be mustered. The directors have canvassed opinion tirelessly, checked on artists from exceptional backgrounds who happen to have studied or worked in Britain, and travelled themselves in search of art. Hawes once took four years out working with Australian aborigines — and came back with a slew of new artists for the gallery.

The present exhibition offers spectacular witness to the gallery’s success. For me, one of its most worthwhile achievements has been its continuing championship of Gerald Wilde (1905-86), the pioneer English Abstract Expressionist and the ultimate bohemian outsider. Another is its support of, and support by, Aubrey Williams (1926-90), whose glowing abstractions bring a whiff of his native Guyana into the often staid purlieus of his later home base in London.

Those choices were bold when made in the late Seventies — and, sadly, remain so. But one thing the gallery has never done is stagnate. Much of the most exciting work in this show comes from recent discoveries, introduced into the international scene for the first time by the October Gallery. Take El Anatsui, he of the bottle-top hanging. He is every inch a sculptor, a master of working with unlikely found materials. Flag for a New Nation looks like a hanging, but is in fact a sculpture, frozen into its apparent folds as though a mighty wind has stopped and the world stopped with it.

Or again, consider Rosella Namok, a 25-year-old Aborigine (and mother of two) who continues to live close to her place of birth in Queensland and paints in a totally individual manner which one would relate to aboriginal art only if one had been told the artist’s origins in advance.

The great characteristic of contemporary native Australian artists is their ability to live happily in two realms at once, both retaining vitalising contact with their traditional culture and relating on equal terms with the 21st-century world outside. If this is what the gallery means by “the ecology of art”, then they have surely found their way with absolute certainty to the heart of it.