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.

Website/Catalog  (1958)  Page(s) [4].  
 
Herbaceous Peonies
Officinalis
Lobata Sunbeam...$2.50

Website/Catalog  (1936)  Page(s) 12.  
 
May-Flowering Pæonies.
Herbaceous Species and varieties.
Single-flowered unless otherwise described.
Lobata Sunbeam. Delightful pale scarlet. In flower June 4th...4/-

Book  (1907)  Page(s) 207.  
 
2413. SUNBEAM; P. officinalis.
(1) 1899, Peter Barr & Son's Cat.
(2) 1900, Cyc. Am. Hort., p. 1191.
(3) 1904, Harrison's Paeony Manual, p. 51.