Duff manages Wharton, and last week he tried to secure a further bet at 5-2 against his man. Bold as ever, he was thinking in thousands. 'I haven't felt as confident about one of my fighters since Michael Watson fought Benn,' he said.
Before the ill-fated Watson took the British and Commonwealth
titles from Benn in May 1989, knocking him out in the sixth round, Duff snapped up long odds against the challenger, thus pulling off a substantial coup.
Few in boxing can match Duff for knowledge and experience, but sometimes subjectivity interferes with his judgement. This can prove costly, as it did in Las Vegas five years ago, when Marlon Starling stopped Lloyd Honeyghan for the WBC welterweight title. As the majority imagined, Starling, at 2-1, was a steal.
To Duff's mind, Wharton's age - 26, against Benn's 30 - and natural strength could be important factors, especially as the champion has expressed thoughts about terminating his lucrative career. 'My guy is younger and a true 12-stone fighter,' he said. 'Benn is a blown-up middleweight.'
More importance could be attached to those advantages if Wharton was better equipped technically, relying mainly on a chilling left hook, and Benn's trainer, Jimmy Tibbs, had not vehemently denied rumours of neglectful preparation. 'Nigel has trained flat-out for this fight,' Tibbs insisted. 'He's in excellent shape.'
If not in the class that has been claimed for him, Benn is nevertheless a much improved boxer who possibly deserved better than a draw against Chris Eubank in their second contest last year. No longer the impetuous slugger who rebuilt his career after the loss to Watson, he will pressure Wharton, but not recklessly. 'I've learned a lot and these days that is more in my mind than a quick finish,' he said.
However, it took Benn only four rounds to demolish Lou Gent, who had been touted as a dangerous opponent after drawing with Wharton in Leeds, alien territory.
But it is not only the form line that suggests a victory for Benn, setting up a contest against Michael Nunn, who is defending the World Boxing Association 12-stone title against another American, Steve Little, on tonight's crowded card.
At 30, Benn may well be nearing the end of a long, hard road and has never been in with a super-middleweight of the highest class, but, comparatively, Wharton is a novice benefiting from astute promotion.
Never reluctant to put his money where his mouth is, Duff thinks otherwise. 'I think Henry will be too strong for Benn, and could even knock him out,' Duff said.
Benn has been wobbled, most revealingly in the dying seconds of a defence against Mauro Galvano of Italy, who might struggle to knock out his sister, but putting him down has been a different matter. Against that, Wharton found great difficulty when matched with Fidel Castro Smith for the British and Commonwealth titles, gaining a controversial decision.
Interestingly, Eubank feels that it is not how hard Wharton drives in his left hook that will matter but how he reacts to Benn's head punches.
The impression is that the champion has trained for a long contest, the conclusion here that he will get the verdict after 12 hard rounds.