London’s Royal Albert Hall opened in 1871 and has long been known for its poor acoustics. “Meanwhile, the celebrated echo belonging to the Albert Hall has been tracked” was printed in Harper’s Bazar (New York, NY) in February 1928.
 
Sir Thomas Beecham (1879-1961) was associated with the London Philharmonic and the Royal Philharmonic orchestras and worked frequently in Royal Albert Hall. “It may be remembered that it was this famous echo that gave rise to Sir Thomas Beecham’s jesting remark that English composers never had work performed twice—unless the performance was at the Albert Hall” was printed in Yorkshire Post and Leeds Intelligencer (Yorkshire, UK) on July 15, 1948. “The Albert Hall’s notorious echo made him (Thomas Beecham—ed.) remark that that was the only place where a British composer could be sure of hearing his works twice” was printed in the Nottingham Journal (Nottinghamshire, UK) on April 29, 1949.
 
   
Wikipedia: Royal Albert Hall
The Royal Albert Hall is a concert hall on the northern edge of South Kensington, London, and is one of the UK’s most treasured and distinctive buildings. The Hall is a registered charity held in trust for the nation, and receives no public or government funding. It can seat 5,267.
 
Since the hall’s opening by Queen Victoria in 1871, the world’s leading artists from many performance genres have appeared on its stage. It is the venue for some of the most notable events in British culture, in particular the Proms concerts, which have been held there every summer since 1941. It is host to more than 390 shows in the main auditorium annually, including classical, rock and pop concerts, ballet, opera, film screenings with live orchestral accompaniment, sports, awards ceremonies, school and community events, and charity performances and banquets.
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In the concert that followed, the Hall’s acoustic problems became immediately apparent. Engineers first attempted to solve the strong echo by suspending a canvas awning below the dome. This helped and also sheltered concertgoers from the sun, but the problem was not solved: it used to be jokingly said the Hall was “the only place where a British composer could be sure of hearing his work twice”.
     
Wikipedia: Thomas Beecham   
Sir Thomas Beecham, 2nd Baronet, CH (29 April 1879 – 8 March 1961) was an English conductor and impresario best known for his association with the London Philharmonic and the Royal Philharmonic orchestras. He was also closely associated with the Liverpool Philharmonic and Hallé orchestras. From the early 20th century until his death, Beecham was a major influence on the musical life of Britain and, according to the BBC, was Britain’s first international conductor.
 
February 1928, Harper’s Bazar (New York, NY), “Lyrical Notes from London” by Frank Swinnerton, pg. 100, col. 1:
Meanwhile, the celebrated echo belonging to the Albert Hall has been tracked.
         
15 July 1948, Yorkshire Post and Leeds Intelligencer (Yorkshire, UK), “Eh! lad!,” pg. 2:
It may be remembered that it was this famous echo that gave rise to Sir Thomas Beecham’s jesting remark that English composers never had work performed twice—unless the performance was at the Albert Hall.
     
29 April 1949, Nottingham Journal (Nottinghamshire, UK), “Bold Venture,” pg. 4:
The Albert Hall’s notorious echo made him (Thomas Beecham—ed.) remark that that was the only place where a British composer could be sure of hearing his works twice.
 
7 January 1951, The Observer (London, UK), “Profile: Thomas Beecham,” pg. 2, col. 4:
That public interest concentrated on his wit and rudery, rather than his music, was partly due to the authentic quality of his wit. Recently, his advice to modern composers was that they should have their works performed in the Albert Hall, as that alone would assure them a second hearing—referring, of course, to that hall’s celebrated echo.
 
13 February 1951, The Christian Science Monitor (Boston, MA), “In Lighter Vein,” pg. 17, col. 7:
Britain’s Beecham
Sir Thomas Beecham’s keen wit is evident in the answer made when asked for advice to Britain’s young composers. He suggested that these musical geniuses have their works performed in London’s famed Albert Hall, as that structure alone would assure them of a second hearing—Beecham was referring to the hall’s famous echo.
   
13 September 1953, The Age (Melbourne,Victoria), “Music in London,” pg. 15, col. 6:
IN SPITE OF EXPERIMENTS with canopies and acoustic experts, “The Echo,” as it has almost affectionately come to be called, seems not seriously to have diminished with the years. (“Get it done at the Albert Hall,” Sir Thomas Beecham is alleged to have advised the aspiring composer of a new ‘opus’: “It’s the only way you’ll be certain of its getting a second hearing.”)
 
10 December 1964, The Christian Science Monitor (Boston, MA), “Like any Olympic runner: Royal Philharmonic” by J. W. Lambert, pg. 10,col. 4:
In central London there is now nowhere for orchestras to play except the Albert Hall which, if you chose the right seat, enables you to hear all the music twice because of a splendid built-in echo!
 
Google Books
The London Spy:
A discreet guide to the city’s pleasures
By Robert Allen, Quentin Guirdham and Hunter Davies
London, UK: Blond
1971
Pg. 168:
THE ALBERT HALL
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Those of the audience in Block K used to hear the music twice because of the echo.
       
Google Books
An Autobiography
By James Galway
New York, NY: St. Martin’s Press
1979
Pg. 86:
What I principal conductor was Lawrence Leonard, with Norman often played in the Duke’s Hall at the Royal Academy,  which has this piece of oneupmanship on the Royal Albert Hall: Sir Thomas Beecham used to say of the latter (because of its notorious echo) that it was the only place in the world where a modern composer could hear his music twice.
   
Google Books
Years of Pilgrimage, an Autobiography
By Raja Ramanna
New York, NY: Viking
1991
Pg. 45:
Musical activity was still restricted to the Albert Hall and the acoustics were by no means ideal. As Thomas Beecham, the great British conductor, wrote in his autobiography: “The Albert Hall is the only place where the work of a British composer gets a second hearing.”
 
Google Groups: alt.music.makers.woodwind
Useless!!
Tom P.
8/17/99
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“The only place a modern composer can hear his music twice” - Sir Thomas Beecham on the echo of The Royal Albert Hall
 
Google Books
The Daily Book of Classical Music:
365 Readings that Teach, Inspire & Entertain
By Leslie Chew, Dwight DeReiter, Cathy Doheny, Colin Gilbert, Greenwood, Travers Huff, Susanna Loewy, Melissa Maples, Jeff McQuilkin and Scott Spiegelberg
Laguna Hills, CA: Walter Foster Publishing, Inc.
2010
Pg. 35:
Sir Thomas Beecham, the orchestral conductor known for his sense of humor, half-joked that the Royal Albert Hall was “the only place a modern composer could hear his music twice.”
     
Twitter     
David Cloke
@DavidCloke
Replying to @KevinWNg
@NonPiuDiFiori Very true. Dreadful barn of a place. Bit like parts of the Albert Hall, you hear every performance twice!
5:20 AM - 8 May 2013
 
Twitter
Martin James
@mememdo
When the Albert Hall was new its acoustics were so bad the Times said it gave British composers best opportunity to hear their work twice.
2:05 PM - 14 Aug 2017
 
Twitter
WIRED UK
@WiredUK
Since it opened in 1871, the Royal Albert Hall’s regal dome created a booming echo of any sound made in the hall. Soon, a joke sprung up: you could hear any piece twice at the Royal Albert Hall. But a clever acoustic redesign is finally fixing the problem
6:00 AM - 3 Apr 2019
 
PSN Europe
Eliminating the echo: A look inside the Royal Albert Hall’s new 465-speaker system
The Royal Albert Hall’s new 465-speaker d&b audiotechnik system, happening to be the biggest single-room audio installation in the world, finally delivers sound fit for a prince
FIONA HOPE May 21, 2019
There’s an old joke about the Royal Albert Hall, the venerable Victorian venue on the southern edge of London’s Hyde Park, that says it’s “the only place where a British composer could be sure of hearing his work twice”. In fact, the hall’s infamous echo – a consequence of its original glass roof – has been almost eradicated in the 148 years since it opened: first, by cladding the glass dome in fluted aluminium panels, and later with its famous disc-shaped fibreglass acoustic diffusers, known affectionately as the ‘mushrooms’, which were installed in 1969.