[15] The Australasian's schools' correspondent declared Denney to be "an all-round runner of great promise",[16] in a report to which was appended a photograph of Denney rounding the last bend (in front of the school's tennis courts) of either the 220 or 440 yards races.
[20] During that time, he played football, in Sydney, along with his future brother-in-law, George Coventry, for the RAAF.
[22] Recruited from Wycheproof in 1947, Denney played in his first senior VFL match, against South Melbourne, on 10 May 1947, on the wing, as a replacement for the injured Des Fothergill.
[24] After his first four games (two on the wing and two on the half-forward flank), he was transferred to the half-back flank, where he played for almost all of the rest of his career,[25][26] including the 1948 Semi-Final (against Footscray),[27] and the 1948 Preliminary Final (against Melbourne), his last VFL game, where he was one of Collingwood's best players, although in a losing team.
[32] Denney was not only the vice-captain of the Wycheproof team that won the 1952 NCFL premiership, defeating the Donald Football Club 15.17 (107) to 4.9 (33),[33][34] but was also the league's best and fairest player that year.