The 24-year-old has spent time training at legendary coach Freddie Roach's Wild Card Boxing Club in Hollywood. It is not only the gym at which 2004 Olympics silver medallist Amir Khan is based, but it is also where Manny Pacquiao transformed into an eight-weight world champion.
Training in such elite company is likely to have further improved the pedigree of a boxer who was born to fight.
Campbell only took the sport up at the age of 13, but such was his ability that he was representing England just two years later. He won the senior ABA bantamweight title in 2007 and then retained the crown in 2008, although he narrowly missed out on a place in the GB team for the Beijing Olympics.
Campbell recovered from that setback, though, as he promptly became the first British boxer to win a European Championship gold medal since 1961 in Liverpool later that year.
Injuries hampered his 2009 campaign, but his trademark speed and accuracy was back for all to see in 2010, when he embarked on a 23-bout unbeaten run. He then claimed a hugely impressive silver medal at the World Championships in Azerbaijan last year.
He has passed up chances to turn professional in order to win Olympic gold, so don't expect him to settle for second best again in London.