Following the retirement of Tom Johnson in 1790, Mendoza claimed the championship of all England.
His claim was further enhanced by the retirement of the reigning all-England champion Ben Brain, in January 1791.
 On 14 May 1792, Mendoza defended the middleweight championship of England in a 23-round, one hour and sixteen minute win against Bill Warr, his former sparring partner, at Smitham Bottom in Croydon.
This cemented his claim and brought him full recognition as the all English champion.
 The title included all weight classes, so the middleweight Mendoza had to defend it against taller, heavier men in the heavyweight class.

After his win against Warr, Mendoza is believed to have met with King George III, formerly the Prince of Wales, at Windsor Palace.
He was the first English Jew to speak to a king.
 Poems and songs were written of Mendoza, he sat for portraits, and was asked to give boxing exhibitions at London's prestigious Covent Gardens.
Mendoza was paid 50 English pounds, an impressive sum in 1790, for several of his boxing demonstrations at Covent Gardens, which he conducted as often as three times a week.

In 1791 Mendoza went on a sparring and exhibition tour of the British Isles with a travelling circus.
 Once in Ireland, he soundly defeated the burly amateur known as "Squire Fitzgerald," who on 2 August had expressed a desire to test his skill with the champion.
Following the retirement of Tom Johnson in 1790, Mendoza claimed the championship of all England. His claim was further enhanced by the retirement of the reigning all-England champion Ben Brain, in January 1791.  On 14 May 1792, Mendoza defended the middleweight championship of England in a 23-round, one hour and sixteen minute win against Bill Warr, his former sparring partner, at Smitham Bottom in Croydon. This cemented his claim and brought him full recognition as the all English champion.  The title included all weight classes, so the middleweight Mendoza had to defend it against taller, heavier men in the heavyweight class.
After his win against Warr, Mendoza is believed to have met with King George III, formerly the Prince of Wales, at Windsor Palace. He was the first English Jew to speak to a king.  Poems and songs were written of Mendoza, he sat for portraits, and was asked to give boxing exhibitions at London's prestigious Covent Gardens. Mendoza was paid 50 English pounds, an impressive sum in 1790, for several of his boxing demonstrations at Covent Gardens, which he conducted as often as three times a week.
In 1791 Mendoza went on a sparring and exhibition tour of the British Isles with a travelling circus.  Once in Ireland, he soundly defeated the burly amateur known as "Squire Fitzgerald," who on 2 August had expressed a desire to test his skill with the champion.
Daniel Mendoza