Question: How long was the original flight being commemorated by the Daily Mail Trans-Atlantic Air Race?

Context paragraphs:
Transatlantic flight of Alcock and Brown: British aviators John Alcock and Arthur Brown made the first non-stop transatlantic flight in June 1919.  They flew a modified First World War Vickers Vimy bomber from St. John's, Newfoundland, to Clifden, Connemara, County Galway, Ireland.  The Secretary of State for Air, Winston Churchill, presented them with the "Daily Mail" prize for the first crossing of the Atlantic Ocean by aeroplane in "less than 72 consecutive hours".  A small amount of mail was carried on the flight, making it the first transatlantic airmail flight.  The two aviators were awarded the honour of Knight Commander of the Most Excellent Order of the British Empire (KBE) a week later by King George V at Windsor Castle.

1937/1938 Daily Mail Gold Cup: The 1937/1938 Daily Mail Gold Cup was a professional snooker tournament sponsored by the "Daily Mail".  The cup was won for the second successive year by Joe Davis with Willie Smith finishing in second place in the final table.  It was the fourth Daily Mail Gold Cup tournament, although only the second as a snooker event.  The Daily Mail Gold Cup ran from 1935 to 1940.

1939/1940 Daily Mail Gold Cup: The 1939/1940 Daily Mail Gold Cup was a professional snooker tournament sponsored by the "Daily Mail".  The cup was won by Alec Brown with Sydney Lee finishing in second place in the final table.  It was the sixth and last Daily Mail Gold Cup tournament, although only the fourth as a snooker event.  The Daily Mail Gold Cup ran from 1935 to 1940.

Daily Mail Trans-Atlantic Air Race: The Daily Mail Trans-Atlantic Air Race was a race between London and New York City to commemorate the 50th Anniversary of the first trans-atlantic crossing by John Alcock and Arthur Brown.

1936 Daily Mail Gold Cup: The 1936 Daily Mail Gold Cup was a professional snooker tournament sponsored by the "Daily Mail".  Despite giving a handicap to all the other players, the cup was won by Joe Davis who won all his five matches.  The Australian Horace Lindrum finished in second place in the final table.  It was the third Daily Mail Gold Cup tournament, although the first two had been billiards events.  The Daily Mail Gold Cup ran from 1935 to 1940.

Daily Mail: The Daily Mail is a British daily middle-market tabloid newspaper owned by the Daily Mail and General Trust and published in London.  It is the United Kingdom's second biggest-selling daily newspaper after "The Sun".  Its sister paper "The Mail on Sunday" was launched in 1982 while Scottish and Irish editions of the daily paper were launched in 1947 and 2006 respectively.  Jonathan Harmsworth, 4th Viscount Rothermere, a great-grandson of the one of the co-founders, is the current chairman and controlling shareholder of the Daily Mail and General Trust, while day-to-day editorial decisions for the newspaper are usually made by a team around the editor, Paul Dacre.

1938/1939 Daily Mail Gold Cup: The 1938/1939 Daily Mail Gold Cup was a professional snooker tournament sponsored by the "Daily Mail".  The cup was won by Alec Brown with Sidney Smith finishing in second place in the final table.  It was the fifth Daily Mail Gold Cup tournament, although only the third as a snooker event.  The Daily Mail Gold Cup ran from 1935 to 1940.

RAF St Pancras: RAF St Pancras was a temporary, but official, Royal Air Force station established in the Somers Town Goods Yard beside St Pancras railway station in London.  The base was opened and closed in May 1969 in order to serve the winning entry of Flt Lt Tom Lecky-Thompson and Harrier XV741 in the Daily Mail Trans-Atlantic Air Race.

No. 1 Long Range Flight RAAF: No. 1 Long Range Flight was a temporary Royal Australian Air Force unit formed to participate in the 1953 London-to-Christchurch air race (also known as the Christchurch Centenary air race).  The flight was established in February 1953 and was equipped with three Canberra bombers, specially modified between June and August.  Following extensive training, two Canberras departed for the UK in mid-September.  The race began on 9 October, and one of the flight's aircraft placed second, with a total flying time of 22 hours and 29 minutes.  The other aircraft was forced out of the race when one of its tyres burst while landing at Cocos Island to refuel, but completed its flight to Christchurch after being repaired.  After a brief period in New Zealand both aircraft returned to Australia to be modified back to a standard configuration, and the flight was disbanded in November.

Daily Mail Circuit of Britain air race: The "Daily Mail" Circuit of Britain air race was a British cross-country air race which took place from 1911 until 1914, with prizes donated by the "Daily Mail" newspaper.  It was one of several races and awards offered by the paper between 1906 and 1925.

Supporting paragraphs: Daily Mail Trans-Atlantic Air Race Transatlantic flight of Alcock and Brown
Answer: less than 72 consecutive hours