Dennis started his career in publishing by being one of the people behind Oz, the Sixties satirical magazine which was prosecuted for conspiracy in 1971. Dennis himself escaped a sentence after the judge made a derogatory comment about his intelligence.
He fought back from this insult, initially building his company on the back of Bruce Lee poster magazines. He was recently named one of the most powerful people in media by The Guardian newspaper and is claimed to be the 56th richest person in Britain. He divides his time between homes in Mustique, New York, and Britain.
In recent times, alongside growing his publishing empire, Dennis has become a published poet with an anthology called A Glass Half Full.