Question: Who was the English conductor and Director of Music for the British Broadcasting Corporation, who first performed Ralph Vaughan William's Symphony No. 6?

Context paragraphs:
Symphony No. 6 (Vaughan Williams): Ralph Vaughan Williams's Symphony in E minor, published as Symphony No. 6, was composed in 1946–47, during and immediately after World War II.  Dedicated to Michael Mullinar, it was first performed by Sir Adrian Boult and the BBC Symphony Orchestra on 21 April 1948.  Within a year it had received some 100 performances, including the U.S. premiere by the Boston Symphony Orchestra under Serge Koussevitzky on 7 August 1948.  Leopold Stokowski gave the first New York performances the following January with the New York Philharmonic and immediately recorded it, declaring that "this is music that will take its place with the greatest creations of the masters."  However, Vaughan Williams, very nervous about this symphony, threatened several times to tear up the draft.  At the same time, his programme note for the first performance took a defiantly flippant tone.

John Reith, 1st Baron Reith: John Charles Walsham Reith, 1st Baron Reith, {'1': ", '2': ", '3': ", '4': "} (20 July 1889 – 16 June 1971) was a British broadcasting executive who established the tradition of independent public service broadcasting in the United Kingdom.  In 1922 he was employed by the BBC (British Broadcasting Company Ltd.) as its general manager; in 1923 he became its managing director and in 1927 he was employed as the Director-General of the British Broadcasting Corporation created under a Royal Charter.  His concept of broadcasting as a way of educating the masses marked for a long time the BBC and similar organisations around the world.

A London Symphony: A London Symphony is the second symphony composed by Ralph Vaughan Williams.  The work is sometimes referred to as the Symphony No. 2, though it was not designated as such by the composer.  First performed in 1914, the four-movement symphony was lost, reconstructed and later modified by Vaughan Williams.

Leith Hill Musical Festival: The Leith Hill Musical Festival (LHMF) was founded in 1905 by Margaret Vaughan Williams, sister of the composer Ralph Vaughan Williams, and Lady (Evangeline) Farrer, wife of Lord Farrer of Abinger Hall. [29] Ralph Vaughan Williams became the Festival Conductor from 1905 to 1953.  The present Festival Conductor is Jonathan Willcocks (appointed June 2016 as the 6th Festival Conductor). [30]

James Westman: James Westman (born September 16, 1972) is a Canadian baritone known for his interpretation of the Verdi, Puccini and bel canto operatic repertoire, and particularly his signature role of Germont in "La traviata", which he has sung in over 150 performances, with opera companies such as San Francisco Opera, Houston Grand Opera, Pittsburgh Opera, Florida Grand Opera, Graz Opera, Santa Fe Opera, Chicago Lyric Opera, Opéra de Montréal, Los Angeles Opera, Grand Théâtre de Bordeaux, Canadian Opera Company, Boston Lyric Opera, Cologne Opera, Vancouver Opera, English National Opera, San Diego Opera, Dallas Opera, Utah Opera, and Opera Theatre of St. Louis.  On January 29, 2011 Westman created the lead role of Sandy Keith In the world premiere of Bramwell Tovey's The Inventor.  In 2017 he played Sir John A. MacDonald in Harry Somers's Louis Riel for the Canadian Opera Company's tribute to Canada's 150th celebrations.  As a recitalist, he has performed for the Marilyn Horne Foundation, Aldeburgh Connection, Aldeburgh Festival, Musikverein, Wigmore Hall, Queen Elizabeth Hall, Morgan Library & Museum, Koerner Hall, Carnegie Hall, Saito Kinen Festival in Japan, Stratford Summer Music, British Broadcasting Corporation, and the Canadian Broadcasting Corporation.  Westman first came to attention at the age of twelve when he was the first boy soprano to perform and record Mahler "4th Symphony" with Benjamin Zander and the Boston Philharmonic Orchestra in 1984.  Westman is regularly featured as the Anthem singer for the Toronto Maple Leafs and numerous other NHL franchises.  Four of Westman's recordings have been nominated for a Juno Award.  Two recordings nominated for a Grammy Award.

Fantasia on Christmas Carols: Fantasia on Christmas Carols is a 1912 work for baritone, chorus, and orchestra by the English composer Ralph Vaughan Williams.  First performed at the 1912 Three Choirs Festival at Hereford Cathedral, the work is a single movement of roughly twelve minutes which consists of the English folk carols "The truth sent from above", "Come all you worthy gentlemen" and "On Christmas night all Christians sing" (i.e. the Sussex Carol), all folk songs collected in southern England by Vaughan Williams and his friend Cecil Sharp a few years earlier.  These are interposed with brief orchestral quotations from other carols, such as "The First Nowell".  The early work remains popular with choral societies, and is sometimes paired with his longer Christmas work "Hodie" of 1954.  There is also a version of the "Fantasia" which replaces the orchestra with strings and organ.  A purely orchestral version, in which the solo vocal and choral parts were 'cued in' on the orchestral instruments, was performed in Studio 8H, New York, on 19 December 1943 by the NBC Symphony conducted by Leopold Stokowski.  The broadcast of this unpublished version, which was presumably arranged by the conductor, has been released on a 'Guild Historical' CD and is also uploaded on YouTube.

The Great War (documentary): The Great War is a 26-episode documentary series from 1964 on the First World War.  The documentary was a co-production of the Imperial War Museum, the British Broadcasting Corporation, the Canadian Broadcasting Corporation and the Australian Broadcasting Commission.  The narrator was Michael Redgrave, with readings by Marius Goring, Ralph Richardson, Cyril Luckham, Sebastian Shaw and Emlyn Williams.  Each episode is  40 minutes long.

Peter Eckersley (engineer): Captain Peter Pendleton Eckersley (P. P. Eckersley, 6 January 189218 March 1963) was a pioneer of British broadcasting, the first Chief Engineer of the British Broadcasting Company Limited from 1922 to 1927 and Chief Engineer of the British Broadcasting Corporation until 1929.  Some sources incorrectly give his middle name as Prothero.

A Sea Symphony: A Sea Symphony is a piece for orchestra and chorus by Ralph Vaughan Williams, written between 1903 and 1909.  Vaughan Williams' first and longest symphony, it was first performed at the Leeds Festival in 1910, with the composer conducting.  The symphony's maturity belies the composer's relative youth when it was written (he was 30 when he first began sketching it).  One of the first symphonies in which a choir is used throughout the work and is an integral part of the musical texture, "A Sea Symphony" helped set the stage for a new era of symphonic and choral music in Britain during the first half of the 20th century.  The work is sometimes referred to as the Symphony No. 1.

Adrian Boult: Sir Adrian Cedric Boult, CH ( ; 8 April 1889 – 22 February 1983) was an English conductor.  Brought up in a prosperous mercantile family, he followed musical studies in England and at Leipzig, Germany, with early conducting work in London for the Royal Opera House and Sergei Diaghilev's ballet company.  His first prominent post was conductor of the City of Birmingham Orchestra in 1924.  When the British Broadcasting Corporation appointed him director of music in 1930, he established the BBC Symphony Orchestra and became its chief conductor.  The orchestra set standards of excellence that were rivalled in Britain only by the London Philharmonic Orchestra (LPO), founded two years later.

Supporting paragraphs: Symphony No. 6 (Vaughan Williams) Adrian Boult
Answer: Sir Adrian Boult