What can Scottish Presbyterians Sing?

In recent years, the commitment of the Free Church of Scotland to exclusive, unaccompanied psalm-singing in "formal" worship services has wavered. The issue, understandably, has divided an already fractured church. The church has taken the unusual step of calling a plenary assembly to discuss the matter. Readers of Ref21 might be interested in the opinion of a dear friend of mine, and a Free Church minister, here.