This section is from the book "The Gardener V1", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
The Canterbury Bell, though a favourite flower, and cultivated of old with more zest than now, has not improved, nor had any very striking feature added to it till within the last few years. The pale-rose varieties are the most marked improvement in colour that have been introduced for a generation or two, but we can now speak of an alteration in the calyx in the present subject, which adds a new interest and value to this old-fashioned flower. In this new variety of Canterbury Bell, the calyx is petal-like in colour, and to some extent it approaches the petal in size also, being much enlarged. At present the calyx is the same colour as the petal - blue or white, as the case may be; but a rose coloured calyx and white petal, or a blue petal and white calyx, or vice versa, may be amongst the possibilities of the not very distant future.