Youth ministry has undergone radical change over recent years.
In the early post-war years it was almost exclusively run by well meaning volunteers who faithfully did their work week by week — the concept of a full-time youth minister was virtually unknown.
I first met a part-time one in the 70s. What became apparent in the 80s was that young people were leaving the church in droves — most of us doing youth ministry at that time could see there was a problem, but when Peter Brierley published his research (Reaching and Keeping Teenagers) the figures confirmed what most of us knew.