In the early 1970s, Dowell began to explore activities away from the ballet stage. Trying his hand at costume design, he created stage wear for himself and Sibley in Ashton's "Meditation from Thaïs" and for dancers in MacMillan's "Pavane", in Balanchine's "Tchaikovsky Pas de Deux" and "Symphony in C", and in Robbins's "In the Night". He also began to look for opportunities beyond Covent Garden. Between 1978 and 1980, he took leave of absence from the Royal Ballet to dance as guest artist with American Ballet Theatre in New York. There he added Solor in "La Bayadère" and Basilio in "Don Quixote" to his roster of leading roles. Along with experiencing the challenges of a new repertory, he partnered such bright stars as Natalia Makarova in "Swan Lake" and Gelsey Kirkland in "Romeo and Juliet". After his official retirement from the Royal Ballet in 1984, he continued to make occasional dance appearances well into his fifties, creating roles in MacMillan's "Winter Dreams" in 1991 and in Peter Wright's production of "The Nutcracker" in 1999.