Question: For how long did John Arlott's workplace alternate different broadcasting systems?

full_context: Document 1: BBC Television: Baird Television Ltd. made Britain's first television broadcast, on 30 September 1929 from its studio in Long Acre, London, via the BBC's London transmitter, using the electromechanical system pioneered by John Logie Baird. This system used a vertically-scanned image of 30 lines – just enough resolution for a close-up of one person, and with a bandwidth low enough to use existing radio transmitters. Simultaneous transmission of sound and picture was achieved on 30 March 1930, by using the BBC's new twin transmitter at Brookmans Park. By late 1930, 30 minutes of morning programmes were broadcast Monday to Friday, and 30 minutes at midnight on Tuesdays and Fridays, after BBC radio went off the air. Baird broadcasts via the BBC continued until June 1932.
Document 2: Joseph Lee (poet): Joseph Johnston Lee (1876–1949) was a Scottish journalist, artist and poet, who chronicled life in the trenches and as a prisoner of war during World War I. He is also remembered for his dispute with then poet laureate Robert Bridges over the literary value of Robert Burns' work. He has been described as "Scotland's 'Forgotten' War Poet", as well as "Dundee's forgotten war poet."
Document 3: High-definition television: Colour broadcasts started at similarly higher resolutions, first with the US NTSC color system in 1953, which was compatible with the earlier monochrome systems and therefore had the same 525 lines of resolution. European standards did not follow until the 1960s, when the PAL and SECAM color systems were added to the monochrome 625 line broadcasts.
Document 4: High-definition television: Since the formal adoption of digital video broadcasting's (DVB) widescreen HDTV transmission modes in the early 2000s; the 525-line NTSC (and PAL-M) systems, as well as the European 625-line PAL and SECAM systems, are now regarded as standard definition television systems.
Document 5: Kenneth Wolstenholme: Kenneth Wolstenholme, DFC & Bar (17 July 1920 -- 25 March 2002) was an English football commentator for BBC television in the 1950s and 1960s. In the final moments of the 1966 FIFA World Cup, he said ``some people are on the pitch... they think it's all over... it is now! ''as Geoff Hurst scored England's fourth goal. The phrase became part of British popular culture.
Document 6: Color television: After a series of hearings beginning in September 1949, the FCC found the RCA and CTI systems fraught with technical problems, inaccurate color reproduction, and expensive equipment, and so formally approved the CBS system as the U.S. color broadcasting standard on October 11, 1950. An unsuccessful lawsuit by RCA delayed the first commercial network broadcast in color until June 25, 1951, when a musical variety special titled simply Premiere was shown over a network of five East Coast CBS affiliates. Viewing was again restricted: the program could not be seen on black - and - white sets, and Variety estimated that only thirty prototype color receivers were available in the New York area. Regular color broadcasts began that same week with the daytime series The World Is Yours and Modern Homemakers.
Document 7: BBC Television: After a series of test transmissions and special broadcasts that began in August, regular BBC television broadcasts officially resumed on 1 October 1936, from a converted wing of Alexandra Palace in London, which housed two studios, various scenery stores, make-up areas, dressing rooms, offices, and the transmitter itself, now broadcasting on the VHF band. BBC television initially used two systems, on alternate weeks: the 240-line Baird intermediate film system and the 405-line Marconi-EMI system, each making the BBC the world's first regular high-definition television service, broadcasting Monday to Saturday from 15:00 to 16:00 and 21:00 to 22:00.
Document 8: Leslie Gay: Leslie Hewitt Gay, born at Brighton on 24 March 1871 and died at Sidmouth, Devon, on 1 November 1949, was a first-class cricketer who played for Cambridge University, Hampshire, Somerset and England. As a footballer, he played for Cambridge University, the Corinthians and England.
Document 9: Leon Belleth: Leon Belleth was a popular announcer with Radio Ceylon and subsequently the Sri Lanka Broadcasting Corporation. He presented a range of radio programs including Holiday Choice. Listeners enjoyed his free and easy style of broadcasting. Leon Belleth was educated at one of Sri Lanka's foremost educational institutions - Royal College Colombo. He was introduced to radio by the veteran broadcaster, Vernon Corea who mentored him while he was in Radio Ceylon.
Document 10: John Arlott: Leslie Thomas John Arlott, OBE (25 February 1914 – 14 December 1991) was an English journalist, author and cricket commentator for the BBC's "Test Match Special". He was also a poet and wine connoisseur. With his poetic phraseology, he became a cricket commentator noted for his "wonderful gift for evoking cricketing moments" by the BBC.
Document 11: George Orwell: David Astor lived in Sutton Courtenay, Oxfordshire, and arranged for Orwell to be interred in the churchyard of All Saints' there. Orwell's gravestone bears the simple epitaph: "Here lies Eric Arthur Blair, born June 25th 1903, died January 21st 1950"; no mention is made on the gravestone of his more famous pen name.
Document 12: Beyond a Boundary: James initially had difficulty finding a publisher, according to his widow Selma James, but on its publication by Hutchinson "Beyond a Boundary" was well received, and John Arlott wrote in "Wisden":"1963 has been marked by the publication of a cricket book so outstanding as to compel any reviewer to check his adjectives several times before he describes it and, since he is likely to be dealing in superlatives, to measure them carefully to avoid over-praise – which this book does not need … in the opinion of the reviewer, it is the finest book written about the game of cricket."
Document 13: BBC Television: After a series of test transmissions and special broadcasts that began in August 1936, the BBC Television Service officially launched on 2 November 1936 from a converted wing of Alexandra Palace in London. ``Ally Pally ''housed two studios, various scenery stores, make - up areas, dressing rooms, offices, and the transmitter itself, which then broadcast on the VHF band. BBC television initially used two systems on alternate weeks: the 240 - line Baird intermediate film system and the 405 - line Marconi - EMI system. The use of both formats made the BBC's service the world's first regular high - definition television service; it broadcast from Monday to Saturday between 15: 00 and 16: 00, and 21: 00 and 22: 00. The first programme broadcast -- and thus the first ever, on a dedicated TV channel -- was`` Opening of the BBC Television Service'' at 15: 00. The first major outside broadcast was the coronation of King George VI and Queen Elizabeth in May 1937.
Document 14: BBC Television: The two systems were to run on a trial basis for six months; early television sets supported both resolutions. However, the Baird system, which used a mechanical camera for filmed programming and Farnsworth image dissector cameras for live programming, proved too cumbersome and visually inferior, and ended with closedown (at 22:00) on Saturday 13 February 1937.
Document 15: BBC Television: Mechanically scanned, 30-line television broadcasts by John Logie Baird began in 1929, using the BBC transmitter in London, and by 1930 a regular schedule of programmes was transmitted from the BBC antenna in Brookmans Park. Television production was switched from Baird's company to what is now known as BBC One on 2 August 1932, and continued until September 1935. Regularly scheduled electronically scanned television began from Alexandra Palace in London on 2 November 1936, to just a few hundred viewers in the immediate area. The first programme broadcast – and thus the first ever, on a dedicated TV channel – was "Opening of the BBC Television Service" at 15:00. The first major outside broadcast was the coronation of King George VI and Queen Elizabeth in May 1937. The service was reaching an estimated 25,000–40,000 homes before the outbreak of World War II which caused the service to be suspended in September 1939. The VHF broadcasts would have provided an ideal radio beacon for German bombers homing in on London, and the engineers and technicians of the service would be needed for the war effort, in particular the radar programme.
ground_truth: six months
sub_queries: What is John Arlott's place of employment? Answer: BBC
For how long did the BBC alternate different broadcasting systems? Answer: six months