The following link gives an even earlier date for Jones' patent - Filed 14
Dec 1928, patented Apr 19th 1932. Nice drawings too.
And just to fill in the gaps - in his book, The Inventor of Stereo: The Life
and Work of Alan Dower Blumlein, Robert Charles Alexander writes, “…on
Friday, 19 January 1934, nine sides were cut of a rehearsal of Mozart's
Symphony No. 41 'The Jupiter', with the London Philharmonic Orchestra,
conducted by Sir Thomas Beecham."