His real name was Johnny Bos, but "The Gravedigger" label was affixed because he was a man with the reputation of digging up "dead bodies" as opponents on whom rising young prospects could hone their skills and learn the trade in the early stages of their careers.

He selected the patsies, the palookas and the pushovers for the promoters and matchmakers who needed soft touches for the tyros they were grooming towards stardom.

It was required for them to be hit - without too much danger of them hitting back to cause costly upsets. Great Britain’s Frank Bruno was among the grateful recipients of the late Bos’s professional services.

Now, if you listen to some critics, it would seem that "The Gravedigger" has himself been exhumed to assist in furthering the fistic education of boxing’s latest heavyweight hope, the London 2012 Olympic champion Anthony Joshua.

He is unbeaten in 11 professional engagements, but none of those he has fought have heard the bell for the end of the third round.

The quality of such opposition is under serious scrutiny.

Of course it is not unusual for young heavyweight prodigies to be fed initially a staple diet of easy pickings but the 6ft 5in Joshua has faced a string of much smaller and older opponents who have punched well below their weight. If at all.

The combined age of the last three is 112. He has yet to meet anyone currently under 30 and three have been in their 40s. One (Matt Skelton, ko’d in one) was 48.

Among those suggesting that Joshua should now be facing stiffer opposition - and not just stiffs - is Frank Warren, the promoter who lost out to rival Eddie Hearn’s Matchroom organisation in the bidding war to sign Joshua when the Londoner decided to cash in his Olympic gold medal.

But Warren insists it is not sour gripes.

"I am one of Anthony Joshua’s biggest fans," he says. "It is no secret that I tried to sign him after he became the London 2012 Olympic super-heavyweight champion as he is a fine prospect who one day may win the world heavyweight title.

"Having said that I am disappointed that the opponents he has faced so far in his professional career have not been stepped up of sufficient quality to test either his durability or his chin - the two big questions that need answering. In my view he fought better opposition as an amateur, certainly in the Olympics, than he has so far as a pro.

"As I say, I really like him. But it is time he started fighting men nearer his own age and size."

His latest friendly foe, the pathetic roly-poly American Jason Gavern, was duly despatched inside three rounds, a predictable outcome as he had been beaten 20 times before and stopped or ko’d in half of those defeats. As a contest, it told us nothing about Joshua’s true professional potential, which is a pity.

Though in mitigation, Joshua had been out of the ring for several months recovering from a back injury so no-one expected him to be pitched in against Deontay Wilder!

But surely it is time he was let off the leash against stiffer opposition - not just rollovers - to see whether he really can be a top dog of war.

As Warren points out, Joshua is no baby. He is 25, just a year younger than Tyson Fury who is now number one contender for Wladimir Klitschko’s WBO title and won the English title in only his eighth fight.

He is due to fight another American, the well-seasoned warhorse Kevin Johnson, who is 35, at London‘s O2 Arena on May 30. Although Johnson has lost four of his last five and is not a noted puncher, he has never been stopped. Hopefully he can take Joshua more than just a round or three so we can finally see what he’s made of.

Warren argues that with a dozen fights under his belt, Britain’s golden boy should then be moving up in class to tackle, say, either Dereck Chisora, David Price or new kid on the block, Brixton’s unbeaten Dillian Whyte, who is 26, has knocked down Joshua and beat him as an amateur. Theirs is a rivalry to match that of James DeGale and George Groves in their vest and headguard days.

There is no argument that Joshua is the most exciting prospect in world boxing today and we must hope that he follows the route of another London-born Olympic super-heavyweight champion, Lennox Lewis and becomes a pro world champion, rather than that of ill-fated Sydney 2000 predecessor Audley Harrison.

Audley’s career, originally built on a succession of personally hand-picked nobodies who couldn't break an egg, sadly has ended in ignominy and possible brain damage. He just couldn't hack it as a top class pro.

Joshua talks the part, looks the part and so far punches the part. But can he act the part when the curtain goes up on the real show once the auditions are over? That’s what the fans want to know. It will take more time, and sterner opposition, to find out.

However, in his defence it should be pointed out that the majority of previous Olympic champions who have gone on to rule the pro professional heavyweight division also had their fair share of knocking over "dead bodies" at comparable stages in their development.

Floyd Patterson, middleweight champion at Helsinki 1952, Muhammad Ali, light-heavyweight champion as Cassius Clay at Rome 1960, heavyweights Joe Frazier (Tokyo 1964) and George Foreman (Mexico City 1968), super-heavyweights Lennox Lewis (Seoul 1988) and Wladimir Klitschko (Atlanta 1996) all faced a long line of names plucked from the pages of boxing’s Who’s He? rather than Who’s Who, and required 20 or 30 fights apiece to achieve title status.

An exception was Leon Spinks, the Montreal 1976 Olympic light-heavyweight champion, who had only seven pro bouts before he fought - and famously beat - Ali.

And American Pete Rademacher, Olympic heavyweight champion in Melbourne 1956, actually fought for the world title in his first pro bout, flooring Floyd Patterson before being ko’d in six rounds.

Joshua may be getting stick for taking on the hopelessly inadequate Jason Gavern in his 11th bout but in his own 11th fight Klitschko was crossing gloves, albeit briefly, with one Biko Botowamungu. No, me neither! Sounds like another one "The Gravedigger" unearthed...

Alan Hubbard is a sports columnist for the Independent on Sunday and a former sports editor of The Observer. He has covered a total of 16 Summer and Winter Games, 10 Commonwealth Games, several football World Cups and world title fights from Atlanta to Zaire.