Book  (1998)  Page(s) 128.  
 
P. lobata 'Sunbeam'
'Improved. The most brilliant colour in hardy flowers; dazzling scarlet'¹; 'large handsome flowers of a glowing scarlet colour'²; 'No other hardy flowers I know can excel this in the brilliance of its colour; 2ft.'³
In catalogues 83 and 125, this is stated to be 'a form selected here...' - perhaps better named 'Sunbeam Smith's Variety'
refs: Hardy alpine plants no. 83:124 (1912)³; Wholesale catalogue 1912-13: 104¹; Hardy alpine and herbaceous plants no 125: 79 (1931)².