According to biographical notes, Costain was enthusiastic about the tri-color carbro photography and actively promoted it.  Because the process was so labor intensive and perhaps because he insisted on personally developing all his photos, there are not as many examples of his color work as one might hope. This abstracted color-field view of hyacinth blooms shows that he was well ahead of the formally arranged style of color photography prevalent at the time.

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Untitled (Hyacinths) 

Harold Costain, 1937 
vintage tri-color carbro print 
10 1/4 × 13 1/4”