Canon retaining headstocks

[Alan J.Birney]

Sometime in the early 1980s, a ring of bells was restored at a place 
called Woodton (Norfolk ?).
In the comic, were a couple of pictures- one of which showed one of 
the smaller bells fitted a canon retainer shaped like an upside 
down "V" .
I have not personally seen many of that shape and was wondering 
what the merits of that design are, and is the design still used.
Also, how many "coffin" style canon retainers did G + J supply and 
was this the only style of canon retaining headstock they used?
How many of the now defunct bellhangers and founders supplied 
canon retaining headstocks?
A lot to answer I know!

Alan