I heard "Chappo" speak many times - including under the big top at Katoomba, at other conferences, in local churches, doing Beach Mission Bible studies and at evangelistic events. John Chapman was one of my teachers at Moore college - teaching the 2nd year preaching subject. More than the lectures I remember his personal feedback sessions after listening to one of my sermons - a real learning experience! He was unique and irreplaceable, but he inspired a generation to be better evangelists, better preachers and better Christians.
It is worth taking the time to watch his memorial service held at St Andrews Cathedral on Saturday 24th November 2012.
The order of service can be found here.
An audio version of Phillip Jensen's sermon can be found here.
The biography by Michael Orpwood, Chappo, For the Sake of the Gospel was published in 1995 and can be ordered from Evangelism & New Churches.
The SydneyAnglicans article about the event can be found here.