What is the origin of the phrase "The People's Champion"

What is the origin, or at least first use, of the phrase "The People's Champion" or "The People's champ?"

Wikipedia has a list of people nicknamed the People's champion, but no comment on its origin.

This question on movies.stackexchange implies that Muhammed Ali had some sort of claim on the phrase, but no mention of origin.

Regarding phrase origins, "first use" is often a hard bar to jump. That is true of 'people's champion' and the very similar 'champion of the people'.

The earliest uses of those phrases that I have found were in 1768 (p. 14, about midway through the last paragraph) and 1690 (p. 33, second line), respectively.

'People's champion' appears in George Saville Carey's 1768 Liberty Chastised: or Patriotism in Chains, a farcical play:

...he has once fairly engaged to liberty's and the people's champion....

'Champion of the people' is used in Thomas D'Urfey's 1690 burlesque poem, Collin's Walk Through London and Westminster:

Whilst I the Lump, th'unfinish'd Cripple
Prove more the Champion of the People;
....