An exhibition of works by Britain’s leading, but somewhat forgotten, conceptual artists of the Sixties and Seventies, a collective known as Art & Language, opens this week, not here, but at the Museum of Contemporary Art in Barcelona (Macba).

What is more, everything in the show belongs to a Frenchman, Philippe Meaille, who owns 800 of their works – a reminder that, from the Sixties on, many British avant garde artists were better received abroad than they were at home.

The “inventors of conceptual art”, according to their long-term dealer, Nicholas Logsdail of the Lisson Gallery, Art & Language was founded in 1967 by four artists who were teaching art theory in Coventry, and expanded to include nearly 50 members over the years, including the leader of a psychedelic rock band.

The earliest works of the Sixties are text works – philosophical musings about art, its function and meaning. In the Seventies, they developed lengthy index systems to record the dialectical nature of their pronouncements. Housed in filing cabinets, these were sought after by museum curators such as Harald Szeeman, who included them in his esteemed Documenta exhibition in Kassel in 1972.

From the Eighties, the collective branched out into paintings – paintings about landscape painting or about historical landmark paintings by Picasso, Malevich, Jackson Pollock or Gustave Courbet. At one stage, they made paintings with their mouths.

Meaille, now in his early forties, first came across their work when he was a student and was intrigued. He had been brought up surrounded by conventional art objects which his father collected. He went out and bought a Nam June Paik video sculpture. There followed works by Lawrence Weiner, Franz West and others, which challenged the idea of what the art object was.

In 1992, he was told about a collection of Art & Language in the Rothschild Bank in Zurich that could be for sale. What he found was a stack of printed certificates from 1966 with instructions to blow the texts up into wall-size pictures or paintings. Excited by the esoteric nature of the works, Meaille bought the whole collection and decided to find more. To finance his acquisitions, he sold his existing collection.

Sitting in the office of his house in the Loire Valley surrounded by text paintings, Meaille enjoys the idea that they can be regarded as art objects; there is something strangely seductive about them. In his drawing room is a large painting after Courbet’s masterpiece Woman With a Parrot in the Metropolitan Museum of Art. Meaille bought it at a sale in Paris two years ago for $30,000. “No one else was bidding, but I think it’s a great piece,” he says.

Otherwise he has bought very little from auction. Few examples come on to the market because the collectors who first bought the work did not do so for speculative reasons, and also because there have not been enough high prices to entice collectors to sell. The highest auction price to date was in 2011 when a painting by Art & Language entitled Incident in a Museum from 1986 sold for $110,500. (Meaille didn’t buy it because he already owned two examples from the same series.) Most of Meaille’s acquisitions have been made privately by tracking down collections through the galleries that first showed their work.

Meanwhile in London, the Lisson Gallery will have an Art & Language show in November, while Tate Britain is planning an exhibition of British conceptual art in 2016 in which Art & Language will play a lead role. Tate has also been building its collection of their works and last year made three important additions.

As Jill Silverman van Coenegrachts, Meaille’s curator who has been managing director of the Lisson Gallery and a partner of the Galerie Thaddaeus Ropac, says: “This is the last undeveloped area of the post-war market. Abstract Expressionism, Pop art and Minimalism have all gone through the roof. Early conceptual art has not. Yet.”