evangelistic services?

My former co-blogger and considerably-older-than-me-friend Donald Ferguson has launched a new blog A Diet of Worms. Donald is a teacher in a Glasgow secondary school (thus he believes in purgatory of sorts) and knows more theology/bible than most in vocational ministry! Theologically, Donald is baptistic and soteriologically Reformed. His latest post is a belter and asks the question as to whether evangelistic services on the Lord's Day are biblical.