Question: Margaret Bailey was the headmistress of which nondenominational boarding school in Sydney?

Context paragraphs:
Ascham School: Ascham School is an independent, non-denominational, day and boarding school for girls, located in Edgecliff, an Eastern Suburb of Sydney, New South Wales, Australia.

Margaret Bailey: Margaret Ann Montgomery Bailey (9 June 1879 – 5 June 1955) was the headmistress of Ascham School in Edgecliff, New South Wales.  During her 30 years as headmistress, her educational philosophy raised Ascham School to prosperity and prominence across Australia.  The school totaled over 400 students at her retirement in 1947.  She was an educator, world traveler, and women's activist.

Wycombe Abbey: Wycombe Abbey is an independent girls' boarding school in High Wycombe, Buckinghamshire, England.  Consistently ranked as one of the top schools regionally and nationally in academic results, the school was founded in 1896 by Frances Dove, who was previously headmistress of St Leonards School in Scotland.  Its present capacity is approximately 615 girls, aged 11 to 18.  The school is situated on a 160 acres campus in central High Wycombe.  The land includes woods, gardens and a lake, and rises up to 500 feet above sea level in the Chiltern Hills.  The freehold is owned by the school; the main house and several buildings at Wycombe Abbey are Grade II* listed.  The current headmistress is Rhiannon Wilkinson.

The House That Screamed (1969 film): The House That Screamed (Spanish: La residencia) is a 1969 Spanish horror film written and directed by Narciso Ibáñez Serrador.  The film stars Lilli Palmer as Señora Fourneau the headmistress of a nineteenth-century French boarding school for girls where the students begin to disappear under unusual circumstances.  The film was also released under the title "The Boarding School".

Piney Woods Country Life School: The Piney Woods Country Life School (or The Piney Woods School) is a co-educational independent historically African-American boarding school for grades 9-12 in Piney Woods, unincorporated Rankin County, Mississippi.  It is 21 mi south of Jackson.  It is one of four remaining historically African-American boarding schools in the United States.  It is currently the largest African-American boarding school, as well as being the second oldest continually operating African-American boarding school.

Margaret Biggs: Margaret Biggs (born 9 July 1929, Orpington, Kent) is a popular and collectible exponent of the girls' School story.  She is best known for her Melling School series of books, first published by Blackie in the 1950s.  The series is set at a weekly boarding school and is unusual in that it shows boarding school life and home life side by side.  The interaction between girls and boys is also atypical of the genre at that time.  The Melling series was republished by Girls Gone By Publishers in the 2000s and the reprints, whilst retaining the original text and artwork, have new introductions by Margaret Biggs, who is ‘taking great pleasure in the republication of her books’.  Ms Biggs has also written two new volumes in the series, "Kate at Melling", set twelve years after the earlier books, and "Changes at Melling", which were published by Girls Gone By Publishers in 2008 and 2009 respectively.

Concho Indian Boarding School: Concho Indian Boarding School (also known as the Cheyenne-Arapaho Boarding School at Concho or Concho Indian School and home to the Concho Demonstration School) was a boarding school for members of the Cheyenne and Arapaho Tribes and later opened to other Native American students.  It existed from 1909 to 1983.  It was located in central Oklahoma, approximately 1 mile south of Concho, Oklahoma and 4 miles north of El Reno, Oklahoma.  The name of the town and school is the Spanish word for "shell" and was named for the Indian agent, Charles E. Shell.

Bosei Sports High School: Bosei Sports High School (Danish: Idrætshøjskolen Bosei ) is a folk high school (non-degree granting educational institution for adults) in Præstø, Denmark, in the campus of the former Tokai University Boarding School in Denmark, a Japanese boarding school.  This school was established by local Danish authorities in conjunction with Tokai University, which had operated the boarding school.

Grennaskolan: Grennaskolan Boarding School is a Swedish boarding school located in Gränna, Jönköping County.  Grennaskolan Boarding School was founded in 1963 by Stockholm University and has today approximately 200 students, half of whom are boarding school students and half of whom are international students.

St. Andrew's School (Rhode Island): St. Andrew’s School (founded in 1893) is a nondenominational boarding and day school located on a 100 acre campus in Barrington, Rhode Island, serving co-educational grades 6-12 and Postgraduate (PG).

Supporting paragraphs: Margaret Bailey Ascham School
Answer: Ascham School