Nimai Chatterji, who has died aged 77, was a collector in the purest sense: out of intellectual curiosity and love for his subject, he created a world-class collection relating to post-1945 avant-garde art and literary movements, from Situationism and Concrete Poetry (where the typographical or visual arrangement of words contributes to the intended effect) to happenings and Arte Povera.

The collection, amounting to tens of thousands of items, contains many media, from artists' books to posters, and from photographs to audio-visual material. Nimai collected original and secondary source material, but also tertiary items, such as postcards that the surrealists collected, or lantern slides that may have inspired Marcel Duchamp. The fruit of this labour is to be found in the Tate Archive, housed at Tate Britain in London, and rivals similar avant-garde holdings in France, Germany and the US. Additionally, from his teens onwards, Nimai corresponded with prominent writers who had met Rabindranath Tagore, including TS Eliot, Ezra Pound and Bertrand Russell, to inquire about their memories of the great Bengali writer and musician. He amassed more than 1,000 letters about Tagore, which he bequeathed to a literary charity in Kolkata.

Nimai was born in that city, one of eight children. His father, Basanta Kumar Chatterji, studied and wrote about Hindu philosophy, and from him Nimai inherited his love of words and concepts. He was educated at Jagabandhu high school, at Presidency College for a period, and then at Charuchandra College, where he completed his degree in Bengali literature. In the early 1950s, he visited and worked at the experimental school that Tagore founded in 1901 at Santiniketan. Here, under the shade of trees, Nimai befriended Amartya Sen (later Nobel laureate in economic sciences); and it was in this small cultural oasis that he met his wife to be, Joya Mukherjee.

In the mid 50s Nimai went to Britain and enrolled at the London School of Printing and Graphic Arts (now London College of Communication) to study graphic design. In his spare time, he would scour flea markets in London and Brighton looking for source material, and from this point onwards, began writing to key avant-garde artists such as Joseph Beuys, Christo, Ian Hamilton Finlay, Raoul Hausmann, George Maciunas, Nam June Paik, Michelangelo Pistoletto, Ed Ruscha and Ben Vautier for documentary material and statements about their work. 

He married Joya in 1962 and, after working at the Indian High Commission, became a contributor, and later producer, for the Bengali department of the BBC World Service. For more than two decades, until his retirement in 1993, he broadcast all manner of art-related subjects – from Herbert Read to Fluxus – in his half-hour programme called Shilpa Prangan (Arts Courtyard), stimulating a vibrant art scene that is still evident today in and around Kolkata. This role at the BBC also gave him the opportunity to travel to the continent to interview personalities in the news and the arts, and he spent any spare time acquiring material in markets and at second-hand bookshops in Belgium, France and Italy. Dividing his time between Britain and Santiniketan, Nimai was also able to help the film-maker Satyajit Ray by liaising, for instance, with the indigenous tribes in the Bengal region for Aranyer Din Ratri (Days and Nights in the Forest), released in 1970. More recently, a book of Nimai's humorous musings, Batil Janjal (Discarded Rubbish), was published in Kolkata.

The Tate completed the purchase of the collection in 2008 – so involved were the negotiations that it had taken more than a decade for the collection to be fully assembled at the gallery. By now Nimai was becoming better known and could be seen at private views, deep in conversation with figures from his youth such as George Melly and Barry Miles.

As the Tate's honorary curator for the Chatterji Collection, Nimai took an active role in helping to document it and to exhibitions where he was always a stimulating companion. The task of listing this wealth of material will now be continued by his friends and colleagues at the Tate and by fundraising for a two-year project to fully catalogue it so that the curtain can be lifted to reveal treasures such as this appreciative response written by Hausmann in 1964: "I seldom met somebody so attentive and so recognising my ideas as you."

Joya died in 2007. Nimai is survived by a brother and a sister.

Naseem Khan writes: Nimai bore his scholarship and breadth of interests lightly. A big bear of a man, he gave the impression of inhabiting his own absurd universe that was full of examples of bizarre human behaviour that he took great pleasure in unearthing.

I first came to know him and Joya in 1968 when I was a member of the Asian Music Circle's classical dance company. Many hours were spent with them and their set of spirited Bengali friends, and when I eventually had children Joya became their unofficial godmother.

The talk in their Golders Green flat – in rooms steadily encroached upon by piles of books and magazines from Nimai's burgeoning collection – was never less than buoyant, covering everything from Indian village games to Baul music to gossip and silly pranks. "Oh Nimai …" Joya would expostulate with affection, as he held the floor with another great riff that combined oddity with minutiae. His range of information and friendships was immense.

At one time in the 1980s, he encouraged me to put together and conduct a series of interviews with critics – from Victoria Glendinning to Tariq Ali – for the BBC World Service, in which each talked about a particular leading Indian writer. It was characteristic that he preferred to inspire others than take centre stage himself.

When Joya – a warm-hearted and generous woman – died suddenly, Nimai's practical underpinning went. It is not unfair to say that his few final years were spent in a fog of grief. But he held fast to his satisfaction over his collection being acquired by the Tate and that – of prime importance for Nimai – it would be accessible to the general public. The enormous archive is a fitting memorial to this extraordinary man, to his combination of single-mindedness, insight and passion.

• Nimai Chatterji, collector, writer and broadcaster, born 30 November 1933; died around 25 December 2010