A prolonged and severe bout of rheumatic fever in his early teens permanently affected his eyesight and he subsequently completely lost sight in his right eye.
Cottle was encouraged by Nash-Williams to become a museum curator but he eventually trained as a schoolmaster, gaining a first in education at Cardiff, and taught at Cowbridge Grammar School.
[2] At the outbreak of the Second World War, Cottle was judged to be medically unfit for active service and instead became a private in the Royal Pioneer Corps, stationed at Huyton.
Here he forged a life-long friendship with the two Iredale sisters, one of whom Hilda Queenie, published a volume on Thomas Traherne in 1935 and deepened Cottle's knowledge and appreciation of the work of the Welsh metaphysical poet, Henry Vaughan, "the Silurist".
Mann had a rich fund of anecdotes about the country in general, and of King Zog and his sisters in particular, whose English tutor he had been, and which Cottle frequently and dramatically recounted.
[2] Cottle was an expert on the writings of the Accrington poet Janie Whittaker (1877–1933), and the Welsh Nonconformist minister, the Revd Henry Maurice (1634–1682), an Independent, who had formerly held the living of Church Stretton, and whose journal for the year of Indulgence, 1672, belonged to him.
He befriended numerous clergy and ordinands in the diocese, and through his roles as Sub Warden, successively at Wills Hall (1947–1948), and from 1948 to 1972 at Burwalls, he was an influential figure in the lives of many generations of undergraduates.