. . . Sir Leonard Halliday, this is a painting (author unknown, at least to me). His family crest is in the upper left corner.
I am not herald enough to blazon accurately, but I think this arms is blazoned as:
Sable, three helmets visored or in profile argent, within a bordure or
The translation, I believe, is: on a black shield with a gold border, three silver helmets with the gold visors closed, viewed in profile.