Sharp Treble?

[Alan J.Birney]

Just branching off a little from discussion of rings of twelve/Dove,
I have never heard of All Saints Basingstoke being described as a 
ring of eight plus a sharp Treble,or Broughton in Furness being 
described as a ring of ten plus a sharp Treble whilst they were an 
eleven bell tower, nor was Accrington-yet there are towers with 
thirteen bells (plus a semitone bell) which can be safely rung as a 
true thirteen(no treble rope falling anywhere silly) yet they are 
often described as a ring of twelve plus two semitones,or a ring of 
twelve plus a semitone(in fact I gather a peal has been rung on a 
true thirteen at Redcliffe),so should we not be classing such towers 
as a ring of thirteen plus semitone.
I have never been to Redcliffe,so I dont know what the circle is, but 
there are towers where a true thirteen can be rung full circle.
Where did the term "sharp treble come from?
Alan