Question: Who founded the largest classical ballet company in Australia for which Roma Egan was notably a senior soloist?

Context paragraphs:
Dance Theatre of Harlem: Dance Theatre of Harlem (DTH) is an American professional ballet company and school based in Harlem, New York City.  It was founded in 1969 under the co-directorship of Arthur Mitchell and Karel Shook.  Milton Rosenstock served as the company's music director from 1981 to 1992.  The DTH is renowned for being both "the first Black classical ballet company", and "the first major ballet company to prioritize Black dancers".

The Australian Ballet: The Australian Ballet is the largest classical ballet company in Australia.  It was founded by J. C. Williamson Theatres Ltd. and the Australian Elizabethan Theatre Trust in 1962, with the English-born dancer, teacher, repetiteur and director Dame Peggy van Praagh as founding artistic director.  Today, it is recognised as one of the world's major international ballet companies.

Ballet Manila: Ballet Manila is a classical ballet institution and dance company in the Philippines.  It currently highlights more than fifty highly trained dancers in the highly rigorous Russian (Vaganova) method of classical ballet.  Locally the company has performed in 47 cities holding more than 4,100 performances.  The company has done tours in Asia, Europe and North America, where it has held more than 140 performances.  The company is most notable for its in-house creative director, principal dancer and prima ballerina Lisa Macuja-Elizalde.  Along with Ballet Philippines and the Philippine Ballet Theatre, Ballet Manila is one of the three major ballet companies in the Philippines.  It regularly holds its performances at the Aliw theater and Star Theater, which are both located within Star City at Pasay City.  The concept of a ballet company by the dancers, of the dancers and for the dancers was the idea of Lisa Macuja-Elizalde when she, along with ballet master Osias Barroso and ten other dancers established Ballet Manila in 1995.

American Ballet Theatre: American Ballet Theatre (ABT) is a classical ballet company based in New York City.  It has an annual eight-week season at the Metropolitan Opera House (Lincoln Center) in the spring and a shorter season at the David H. Koch Theater in the fall; the company tours around the world the rest of the year.  ABT was founded in 1939 by Lucia Chase and Richard Pleasant and is recognized as one of the world's leading classical ballet companies.  ABT is also the parent company of the American Ballet Theatre Jacqueline Kennedy Onassis School, and was recognized as "America's National Ballet Company" in 2006 by the United States Congress.

Cairo Opera Ballet Company: The Cairo Opera Ballet Company is the resident ballet company of the Cairo Opera House and a ballet school affiliated to Egypt's Higher Institute of Ballet.  Its foundation began in 1958 during the presidency of Gamal Abdel Nasser through the efforts of Tharwat Okasha, Egypt's culture minister at the time, and Leonid Lavrovsky, the former artistic director of the Bolshoi Ballet who took a group of Egyptian dancers to Russia for two years of training.  At the time of its founding, it was the only Arab resident classical ballet company in the Middle East.

Ballet Austin: Ballet Austin is the 12th largest classical ballet company in the USA, and also operates the largest combined training facility associated with a professional ballet company in the United States.  Each year the Ballet Austin company performs ballets from a wide variety of choreographers, including Stephen Mills.

English National Ballet: English National Ballet is a classical ballet company founded by Dame Alicia Markova and Sir Anton Dolin and based at Markova House in South Kensington, London, England.  Along with The Royal Ballet, Birmingham Royal Ballet and Scottish Ballet, it is one of the four major ballet companies in Great Britain.  English National Ballet is one of the foremost touring companies in Europe, performing in theatres throughout the UK as well as conducting international tours and performing at special events.  The Company employs approximately 67 dancers and a symphony orchestra, (English National Ballet Philharmonic) and there is also an associate school, English National Ballet School, which is independent from the ballet company.  The Company regularly performs seasons at the London Coliseum and has been noted for specially staged performances at the Royal Albert Hall.  In 2014 English National Ballet became an Associate Company of Sadler's Wells.  The Patron of English National Ballet is HRH The Duke of York.

Roma Egan: Roma Egan (born 28 March 1948) was a child actress on Australian television, and an Australian ballet dancer and teacher.  She was notably a senior soloist for The Australian Ballet, and variously performed for the Queensland Ballet, Basel Ballet, Ballet Victoria and Royal New Zealand Ballet.

The Royal Ballet: The Royal Ballet is an internationally renowned classical ballet company, based at the Royal Opera House in Covent Garden, London, UK.  The largest of the four major ballet companies in Great Britain, the Royal Ballet was founded in 1931 by Dame Ninette de Valois, it became the resident ballet company of the Royal Opera House in 1946 and was granted a royal charter in 1956, becoming recognised as Britain's flagship national ballet company.

Boston Ballet: The Boston Ballet is an American professional classical ballet company based in Boston, Massachusetts.  The company, founded in 1963 by E. Virginia Williams, and Sydney Leonard, was the first professional repertory ballet company in New England.  Boston Ballet’s national and international reputation developed under the leadership of Artistic Directors Violette Verdy (1980–1984), Bruce Marks (1985–1997), and Anna-Marie Holmes (1997–2000).  Today, Boston Ballet is one of the major ballet companies in North America and among the top companies in the world.  Current Artistic Director Mikko Nissinen was selected to lead Boston Ballet in September 2001.  Under his artistic direction, Boston Ballet maintains an internationally recognized repertoire of classical, neo-classical and contemporary works, ranging from full-length story ballets to masterworks by George Balanchine, to new works and world premieres by contemporary choreographers.  Nissinen leads the company, and Boston Ballet School, the largest ballet school in North America, with Executive Director Meredith (Max) Hodges.

Supporting paragraphs: Roma Egan The Australian Ballet
Answer: J. C. Williamson Theatres Ltd. and the Australian Elizabethan Theatre Trust