There isn't much Internet biographical information on Collings, so his Wikipedia entry will have to do for now.
Collings' subjects seem to have been mostly women. He painted non-portrait work, but the interesting examples I found are not quite safe for viewing in an office setting. These can probably be found via an Internet search engine.
This is the earliest painting I can document: he was about 40 at the time.
Women posing wearing kimonos was an artistic fashion in those days.
Striking lady strikingly painted.
She modeled for Collings more than once. I think she is the woman in the previous image and perhaps in "The Blue and Gold Dress" above..
Might be a Great War widow,
A number of artists made similar paintings. I'm not sure if His Majesty posed for Collings or if photographs were used. The king's height seems slightly exaggerated.
Based on what Google image searches turned up, this might be Collings' best-known work. The model might be Yasmin.