He wrote what may be the earliest published defence of homosexuality in English, Ancient and Modern Pederasty Investigated and Exemplify'd (1749)[2] and may also have collaborated with John Cleland, author of Fanny Hill.
Just before the second volume appeared, Cannon lodged a legal complaint against Cleland, claiming that he was now sending anonymous letters containing abusive and slanderous accusations.
[5] Despite its illegal subject matter, the pamphlet might never have come to the attention of the authorities had it not been for the embittered Cleland who, after being released from prison for debt, was re-arrested in 1749 for obscenity due to Fanny Hill.
[4] Cannon's mother successfully petitioned the Duke of Newcastle for the charges against her son to be dropped, claiming he was repentant, and indeed, wished to return to England not only because of financial necessity, but in order to publish a retraction or recantation of the original pamphlet.
What remains of Ancient and Modern Pederasty Investigated and Exemplify'd shows that rather than being a dry treatise, it is a somewhat gossipy and jokey anthology of homosexual advocacy, written with an obvious enthusiasm for its subject.