James O’Brien, at Marian, Harrow-on-the-Hill, to Bowles, 17 Apr 1911
John W. Odell, at The Grove Farm, Stanmore, Middlesex, to Bowles, 11 Aug 1904
John W. Odell, at The Grove Farm, Stanmore, Middlesex, to Bowles, 3 Aug 1911
Keith O’Leary, at Boyce Thompson Institute for Plant Research, Yonkers, United States of America, to Bowles, 15 Jun 1934
Sidney Olivier, Secretary, at Board of Agriculture and Fisheries, Whitehall Place, London SW, to Bowles, 29 Feb 1916
The O’Mahony, at Coolballintaggart, Aughrim, County Wicklow, Ireland to Bowles, 14 May 1923 (this letter was found in Mea Allan’s papers and inserted here in 2016)
The O’Mahony, at Coolballintaggart, Aughrim, County Wicklow, Ireland, to Bowles, 2 Jul 1923
The O’Mahony, at Coolballintaggart, Aughrim, County Wicklow, Ireland, to Bowles, 21 Aug 1923
The O’Mahony, at Coolballintaggart, Aughrim, County Wicklow, Ireland, to Bowles, 18 Dec 1923
The O’Mahony, at Coolballintaggart, Aughrim, County Wicklow, Ireland, to Bowles, 28 Jan 1924
The O’Mahony, at Coolballintaggart, Aughrim, County Wicklow, Ireland, to Bowles, 20 Nov 1925