Possible Clues:

• Crumpets cooked in a range of colour!
• Crumpets can provide the full array of colours
• Range of colour produced by a prism
• Crumpets can provide the full array
• Broad range, of colours say
• Is the R.A. in with a bow for this?
• The bands of colur as seen in rainbow
• How colourful to start to speculate if one might get a drink after tea!
• Whole range of colours
• Some may respect Rumpole's full range