Maen was born in Ballymena, Northern Ireland and began his career working as a dancer in Patricia Mulholland's Irish dancing school.
[1] After qualifying in teaching, he moved to Vancouver, British Columbia, Canada where he worked with the Alan Lund Dancers on a weekly television series which starred Robert Goulet.
He is most remembered for his Swine Lake sequence on The Muppet Show which featured Rudolf Nureyev dancing with a giant pig.
One of his other well-remembered works is his version of Claude Debussy's Prélude à l'après-midi d'un faune for Olympic champion skater John Curry.
He choreographed Les Demoiselles de Rochefort with music by Michel Legrand and direction by Jacques Demy, giving him the opportunity to work with Kelly again plus Catherine Deneuve, George Chakiris, Françoise Dorléac and Grover Dale.