[2] Mann was born at Sidcup in Kent and educated at Harrow School and Trinity College, Cambridge.

[5] He captained the cricket team to victory in the Eton v Harrow match at Lord's in 1901, scoring 69 runs in an innings which was described as "fine and attractive".

[10] His form as a batsman was generally steady and it was not until his final season at Cambridge that he stood out, topping the Cambridge batting averages with 758 runs at an average of 46.05 runs per innings, including scoring both of his first-class centuries.

[11] His Wisden obituary described Mann as "a hard-hitting batsman with free style and special strength on the leg-side" and as "a useful change bowler",[10] although he played little first-class cricket after leaving university, at least in part due to business commitments.

[12] In 1905 Mann captained an MCC side which toured North America, playing in both first-class matches against the Gentlemen of Philadelphia, the last of his career.