Mynn was born at Goudhurst in 1807 and stood out from his teens as physically the largest cricketer of his generation. He bowled fast roundarm — the new style legalised in 1828 and refined in 1835 — at a pace that contemporary batsmen, padless and gloveless until the late 1840s, found genuinely intimidating. By the early 1840s he was the leading wicket-taker at Lord's and Canterbury and the senior bowler in the Kent eleven that Pilch's batting was built around. He had nearly lost his leg to a bruise infection at Leicester in 1836, when, having batted on with massive injuries to score 125 not out and 21 not out for the South against the North, he was reportedly carried by stage coach back to London on the roof to lie flat, and survived only after the surgeon at St Bartholomew's drained the wound. The Leicester match made him a national figure; the leg, against medical expectation, was saved. Mynn played single-wicket for high stakes — an ancient form of cricket in which two or three players a side would face each other for purses of £100 or more — and was champion of England from 1838 until 1846. His career was bracketed by the foundation of the All-England Eleven, of which he was a leading member from 1846, and by the gout and money troubles that overtook him in his last years.