Theo Waddington grew up with art. It stood him in good stead for becoming a dealer and, now, an exhibitor, writes Aidan Dunne.

Theo Waddington sits in the midst of the exhibition he has assembled in the atrium of the Office of Public Works on St Stephen's Green. The show, which is called 20th Century Masters, is a remarkable collection of work by some illustrious names in art history: Matisse, Raoul Dufy, André Derain, Henry Moore, Jack B. Yeats, William Orpen, Mainie Jellett and Henri Hayden. It has the air of being a personal collection, lovingly built, but all of the work is for sale.

"I'm an art dealer, born and bred," he says. "So it's not a personal collection in that sense, it's part of my inventory." But at the same time he clearly loves the work, loves each piece. And he is in the unusual position of having known or knowing many of the artists personally.

Theo is the youngest son of Victor Waddington, the art dealer who played a pivotal role in progressing the cause of modern art in Ireland through his gallery in Dublin, his publications, his touring exhibitions and the sheer power of his personality. Victor started selling pictures in the early 1920s and opened his first gallery in 1925, thereafter occupying several premises until he eventually left Ireland for London in 1957. An exceptionally dynamic and imaginative dealer, he not only nurtured many Irish artists but also introduced the work of major international figures to the Irish.

He is perhaps best known in Ireland for his close relationship with Jack B. Yeats, whose cause he championed from 1943. "I don't remember when Yeats wasn't part of my life," Theo says. For his 13th birthday he got a present of a small Yeats titled The Birds Are On The Move, inscribed: "From the youngest Yeats to the youngest Waddington."

Yeats was, he says, like a father to Victor and taught him a great deal about the art business. On the other hand, Victor was an exceptionally loyal dealer and friend to Yeats.

When the artist had moved into Portobello nursing home, Victor visited him every evening after close of business. One evening, sitting by his bed, he fell asleep. To his surprise, Yeats subsequently produced a painting, Sleep, depicting him snoozing in his chair.

Theo inherited a great deal of material relating to Yeats, including a log of the day on which every painting was completed. "Once a painting was finished he'd leave it for a year before signing it. So I had a record of completion and signing, plus numerous letters and mementoes."

Through Victor he came to know other Irish artists, including Louis le Brocquy, Dan O'Neill and Gerald Dillon, Irish collectors such as Howard Robinson and such central art-world figures as James White.

He has an enormous affection for Dublin, where he grew up, living in Rathgar and attending High School on Harcourt Street. "There are very few places where you get that sense of comfort. It was always a very friendly place."

He learned the trade from his father and has followed in his footsteps in formulating this exhibition. "I've deliberately placed Irish artists in the context of people like Matisse and Dufy because they are all on a par; they are all great artists. There is a tendency to segregate Irish artists when they should be seen as equals. I want to see them recognised as major figures internationally. I've said before that it's as much a disadvantage to be an Irish visual artist as it is an advantage to be an Irish writer."

After university and a year spent working in Victor's London gallery, Theo moved to Canada in 1966 and was based there for about 18 years, becoming involved in what sounds like an ever widening network of galleries: Montreal, Toronto, New York, Florida.

He has relinquished these involvements now, closing New York and Florida and passing the Canadian galleries on to the managers. From 1978, when his father became seriously ill, he renewed his involvement in the London gallery, but that too is now gone, although his brother still has a gallery on Cork Street.

"About three years ago we decided that we would come home to Ireland - well, for me it was coming home." They bought a house in Ballycotton, in Co Cork. "It's an incredibly comfortable place to live. If I never moved out of there again I'd be quite content."

In Canada, he continued to "spread the word" about Irish artists, and it is by dint of his efforts that works by many 20th-century Irish artists found their way into Canadian collections: Colin Middleton, Gerald Dillon, Dan O'Neill and, of course, Yeats. "I organised a substantial Yeats show in Toronto in 1972." In fact a remarkable story emerged from that exhibition. Victor had known Samuel Beckett well. In the late 1930s, Beckett set his eye on two small paintings by Jack Yeats. They were, Theo recalls, something like £30 apiece at the time, and Beckett didn't have the money.

"My father was a firm believer in the never-never. He felt people should have access to the paintings they wanted." So he made Beckett an offer. Why not pay a fiver a month for a year? The writer grabbed the chance and got his two Yeats paintings.

"Now," Theo says, "flash forward to 1972. I'm rounding up Yeats paintings from all over for this show, including from collections in the United States and Europe. One day a brown paper parcel tied with strong arrives. I undo the string.There are Beckett's two Yeats paintings, completely unprotected, with a note, in which he said my father did him a great favour in allowing him to acquire them and now he wanted to return the favour."

Somehow he'd heard about Theo's show. All he asked was that the paintings be looked after and returned at some stage. Theo duly included them in the show and guided them, rather more carefully packaged, back to their owner.

During his time in Canada, he started making trips north to the Arctic, to a remote Inuit community. "I went up for shooting and fishing" - caribou and arctic charr - and continued to do so annually.

While there he came into contact with Inuit carvings of polar bears, walruses, birds and human faces and figures. In an adjunct to the show of work by Yeats, Dufy et al, he has included a number of these soapstone pieces, together with photographs of the Arctic and of the Inuit sculptors by John Reeves.

There is also an odd Matisse connection. "Matisse never met an Inuit in reality, but he did a series of lithographs of Inuit faces for a book by his anthropologist son-in-law, George Duthuit, and by comparing them with John Reeves's photographs you can see he was spot on. He worked from artefacts."

The highlights of the show include a dazzling tapestry by Matisse, a clutch of fine oils, watercolours and drawings by Yeats - "If a Waddington can't come up with some good Yeatses it would be a pretty poor reflection" - beautiful Dufys, a very good large Mainie Jellett abstract and some very fine paintings by Henri Hayden, the French artist who, although never as famous as some of his contemporaries, is certainly their equal and was a close friend of Beckett (who introduced him to Victor).

Theo reckons on doing a show a year in Dublin. "For next year, I'm working on the idea of getting together about 40 pieces by Yeats, making it an all-Yeats show."

20th Century Masters is at the Office of Public Works until November 21st