How long was the original flight being commemorated by the Daily Mail Trans-Atlantic Air Race?
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. Transatlantic flight of Alcock and Brown:  They flew a modified First World War Vickers Vimy bomber from St. John's, Newfoundland, to Clifden, Connemara, County Galway, Ireland. Transatlantic flight of Alcock and Brown:  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".
less than 72 consecutive hours