As a comedian, Dennis performed in social clubs all around the northwest of England. He was given his earliest opportunities in his home city of Liverpool, later crediting husband-and-wife theatrical agents Stuart and Dorene Gillespie (who had themselves been a successful variety act) with discovering him in his autobiography. His debut radio broadcast was in 1971 on Stuart's BBC Radio Merseyside series "Variety Time" (the programmes were taped in front of a live audience in Merseyside clubs). In 1974, he won the ITV talent show "New Faces" and appeared on numerous light entertainment shows. He almost became the first contestant ever to score the maximum 120 points on "New Faces", but had to settle for 119 when Tony Hatch gave him 9 out of 10 in his final mark, drawing derision from the rest of a judges panel that included fellow Liverpool comedian Arthur Askey.