William Forsythe is renowned as one of the brainiest and most theoretical of choreographers. Yet when we talk on the telephone, a good deal of time is given over to his fondness for Downton Abbey – a conversation which reveals in-depth knowledge of the British series. “Maggie Smith is so brilliant. And Matthew and Lady Mary. And some of the kitchen help I am very fond of,” he says, swooping on the words, laughter in his voice. Given that his Forsythe Company is based in Frankfurt and Dresden and that he is American, such devotion is impressive. But it is also typical of the man. Forsythe’s entire career has been driven by an overriding curiosity which pushes him to explore both the most abstruse (pure maths, philosophical theory) and the most mundane (he can also quote in perfect imitation from The Fast Show.) He combines that probing intelligence with an unrivalled understanding of the history of dance, and both qualities are on full display in the dazzling Artifact, which gets a rare outing in Britain next week, courtesy of the Royal Ballet of Flanders. Ironically these performances, at Sadler’s Wells and in Birmingham, will be a kind of swan-song for the company’s director, Kathryn Bennetts, who has transformed the company in her seven years in charge, but who has just been ousted from her post in a bitter row with the Minister of Culture. “I just hope we finish with a bang and it looks great,” she says, her voice heavy with emotion. Artifact was created in 1984 and is the first full-length work that Forsythe made in his years in charge of Frankfurt Ballett, a time when he began consciously to extend the language of ballet into a new fractured, hyper-extended and inquisitive form fit for the late 20th century. “I had to find my way around Balanchine, Petipa, Cranko, MacMillan, the whole crowd,” he says. “I realised I had to move on.” His progress took place, as that remark makes clear, in the context of all that had gone before, and Artifact, a four-act ballet apparently in the traditional mode, is a ballet about ballet – or as Bennetts describes it “Bill’s ode to ballet”. The starting point was the Chaconne from Bach’s Partita No 2 in D minor for solo violin, which forms the music for the second act. Forsythe’s rehearsal pianist, at that time, was a woman called Eva Crossman-Hecht, a Juilliard-trained concert pianist. Her “very strict, classical improvisations”, based on the Bach, became the score for the rest of the piece, now transcribed and played live by a single pianist. Forsythe made the entire piece – for a company of more than 30 dancers – in three weeks, weaving a complex web of thought into the piece. Just as the music is based on the ordered world of Bach, so the choreography is based on the basic elements of ballet technique, with the dancers following the instructions of a ghostly woman in grey: “It is about the process of people imitating one another,” Forsythe explains. “Of replication. That is what one does. One starts by standing behind someone else and imitating what they do.” In dance or in life? He laughs. “Well, maybe both. I think it is not a bad metaphor.” Other ideas were also in play. Forsythe had been reading an essay by Lincoln Kirstein, who helped George Balanchine found New York City Ballet, about the critical moment when ballet is emancipated from opera. So he introduced into Artifact a Woman in a Historical Costume who talks in a kind of recitative – and argues throughout with A Man with a Megaphone (played since the very start by Nicholas Champion). He had also been studying the 18th-century dancer known as le Grand Dupré, “a co-ordinative wonder”, whose virtuosity was the basis of later dance technique. “He improvised on the violin while he danced. At that point ballet was still improvisatory and I found that thoroughly liberating,” says Forsythe. Such thoughts provided the background tapestry to a work in which the first words the woman says are “Step inside” – in ballet terms pas en dedans and the last are the man’s are “Step outside”, or pas en dehors. In between those two contradictory instructions, Forsythe examines ballet language, history, Cartesian dualism. He does so in startling choreography, with massed ranks of dancers crossing the stage in what the critic Rosyln Sulcas describes as “a dizzying variety of combinations, rhythms and patterns”. With so much going on, it is no wonder that Artifact saw people gawping in incomprehension as well as cheering at its audacious difference. But throughout his long career of experiment, which continues now with his smaller but still cutting-edge dance company, Forsythe has become used to people not understanding his thought process. However, he would like to correct one common assumption. In the second act, the movement is interrupted by the curtain falling and this is generally regarded as a post-modernist disruption. “That is a musical caesura,” he says, with a hint of irritation. “It wasn’t designed as a disturbance or anything. There is a change in the music each time, so it is giving you the structural chunks of the music.” For Bennetts, who worked as ballet mistress at Frankfurt Ballett for 15 years, the work was revelatory. “I have always thought it was just a masterpiece,” she says. Under her directorship, the Royal Ballet of Flanders has also performed another early full-length Forsythe work, Impressing the Czar, but she has waited to stage Artifact until she felt her dancers were ready. “It pushes them, makes them improve as artists.” It is particularly sad for her, therefore, that the company is performing the work just as she is leaving it in acrimonious circumstances following the Minister of Culture’s announcement that a single director was going to run the ballet and opera companies. “The official line about why I am leaving is that I am too ambitious,” she says. “So that means one of the qualities for a new director is that they should not be ambitious. It is laughable.” Certainly Bennetts’s vision for the company has placed it on the international dance map and it seems fitting that her last work in formal charge is Artifact, a piece that has continued to challenge and enthral audiences. “It still looks as new as ever,” says Bennetts. Forsythe only partially agrees. “I thought it was quite classical,” he says, laughing again. “But it is certainly true that no one else has made a full-length work quite like that.”