Question: What opera was composed by an english composer who was born on the 12th of October 1872 and died on the 26th of August 1958?

Context paragraphs:
John Unstead: John Unstead (9 February 1790 – 22 October 1872) was an English cricketer who played for Kent.  He was born and died in Waldron.

Ernesto Madero: Ernesto Madero Farías (12 October 1872 – 2 February 1958) was a Mexican banker who served as Secretary of Finance in the cabinet of his nephew, President Francisco I. Madero.

Ralph Vaughan Williams: Ralph Vaughan Williams {'1': ", '2': ", '3': ", '4': "} ( 12 October 1872– 26 August 1958) was an English composer.  His works include operas, ballets, chamber music, secular and religious vocal pieces and orchestral compositions including nine symphonies, written over nearly fifty years.  Strongly influenced by Tudor music and English folk-song, his output marked a decisive break in British music from its German-dominated style of the 19th century.

Joseph Holbrooke: Joseph Charles Holbrooke (5 July 18785 August 1958) was an English composer, conductor, and pianist.

Jean-Marie Beurel: Jean-Marie Beurel was born on 5 February 1813 at Plouguenast, in Lower Brittany, France.  He was assigned to the Mission of Siam by the Missions Étrangères de Paris and arrived in Singapore on 29 October 1839 at the age of 26.  He was responsible for the construction of the Church of the Good Shepherd - now the cathedral church of the Archdiocese of Singapore - and worked in the Mission for the next 29 years till 1868 when he returned to France on account of illness.  He died in Paris, France on 3 October 1872 at the age of 59 and was buried in the Montparnasse Cemetery.

James Guthrie (Australian politician): James Francis Guthrie (13 September 1872 – 18 August 1958) was an Australian politician.  Born at Rich Avon Station in Victoria, he was educated at Geelong College before becoming a grazier, sheep breeder and woolbroker.  In 1919, he was elected to the Australian Senate as a Nationalist Senator for Victoria.  In 1931, together with the rest of his party, he joined the United Australia Party.  He held the seat until his defeat in 1937, taking effect in 1938.  Guthrie died in 1958.

Nina Grosse: Nina Grosse (born 11 August 1958) is a German film director and screenwriter.  She has directed 14 films since 1983.  Her 2004 film "Olgas Sommer" was entered into the 26th Moscow International Film Festival.

Symphony No. 9 (Vaughan Williams): The Symphony No. 9 in E minor was the last symphony written by the British composer Ralph Vaughan Williams.  He composed it from 1956 to 1957 and it was given its premiere performance in London by the Royal Philharmonic Orchestra conducted by Malcolm Sargent on 2 April 1958, in the composer's eighty-sixth year.  It was subsequently performed on 5 August 1958 by the BBC Symphony Orchestra under the direction of Malcolm Sargent at a Promenade Concert.  Vaughan Williams died three weeks later, on 26 August, the very day on which the symphony was due to be recorded for the first time, by the London Philharmonic Orchestra conducted by Sir Adrian Boult.  The composer had planned to attend the recording sessions.

Lovely Joan: Lovely Joan is a traditional English folk song (Roud #592), and the tune to which it is sung.  Its melody is most familiar to modern audiences as the counterpoint tune used in British composer Ralph Greaves's arrangement of "Fantasia on "Greensleeves"" from Ralph Vaughan Williams's opera "Sir John in Love"."

Cassius Clement Stearns: Cassius Clement Stearns was an American composer of church music.  He was born on 23 August 1838 in Ashburnham, Massachusetts, the youngest child of Charles Stearns (1796-1874) and Rebecca Green Stearns (née Robbins) (1802-87).  He married Gertrude Bottomly (1837-1910) of Leicester, Massachusetts, in Boston on 23 October 1872 (a few days before the Great Fire), the celebrant being the Revd.  Phillips Brooks.  Stearns died on 7 August 1910 in Sharon, Massachusetts and is buried at Worcester Rural Cemetery, Grove Street, Worcester.

Supporting paragraphs: Lovely Joan Ralph Vaughan Williams
Answer: "Sir John in Love"