[11] No record exists of football matches from Thring's time at Shrewsbury, but he is known to have played on the school cricket team in 1842 and 1843.

According to N. L. Jackson, in 1846 "two old Shrewsbury boys, Messrs H. de Winton and J. C. Thring, persuaded some Old Etonians to join them and formed a club.

[13] According to Thring's own account, written in 1861:[3] [I]n 1846, when an attempt was made to introduce a common game, and form a really respectable club, at Cambridge, the Rugby game was found to be the great obstacle to the combination of Eton, Winchester, and Shrewsbury men in forming a football club.This was among the first of several known attempts to formulate a set of "compromise" rules of football at Cambridge between alumni of different schools.

[16] During his time as a resident master at Uppingham (1859–1864), Charles Thring became intensely involved in efforts to create a common code of football.

[17] Thring immediately responded with a letter criticising the Rugby code in strong terms, referring to its allowance of "hacking" (kicking opponents' shins) as "a blot", "thoroughly un-English", and "barbarous".

During the first half of 1862, Thring continued to engage in discussion of the merits of different rules of football via correspondence published in The Field.

In a letter dated 13 November, Thring wrote that Uppingham School was "extremely desirous of joining" the association.

[21] These letters made a notable contrast with the generally negative attitude of other public schools (Charterhouse and Harrow had both refused to participate, Shrewsbury would subsequently do so, and Rugby, Eton and Winchester failed to reply at all).

He repeated his objection to the use of the term "touch", and also expressed disapproval of the FA offside law, which had been relaxed the previous year.

[32] Thring also objected to the "touch down" tie-breaker which had been introduced by the FA in 1866; this was removed from the laws as the result of a proposal by Wanderers FC.

[41] Thring's set of laws is also acknowledged as the inspiration behind the title of Paul Gardner's 1976 book The Simplest Game.

[42] Thring continued to serve as master at Uppingham until 1868 or 1869,[4][43] but in 1864, following a dispute with his brother Edward,[44] he and his wife ceased to live at the school,[45] instead residing at the Chantry House at Bradford-on-Avon.