Marcia Anastasia Christoforides (1909-1994)  became Lady Dunn through her marriage in 1942 to Sir James Dunn, a Canadian financier 36 years her senior, who died in 1956. In 1963 she married Max Aitken, Lord Beaverbrook, who was 31 years her senior, and died the following year - Beaverbrook said "she was the first woman he'd had who was richer than he was." 

She also sat to Salvador Dali for his Equestrian Fantasy of 1954. 'Christofor', as she was known, was a keen horsewoman and racehorse owner (her colours being green and brown). In 1971 she escaped a car bomb placed by the Angry Brigade which was detected before it went off. Imperious but astute, she was a very generous benefactor to many causes.

We are told (by Inez Tobin) that the heart in the top right corner is an acrostic device, spelling DEAREST with Diamond, Emerald, Amethyst, Ruby, Emerald, Sapphire and Topaz. It is likely that Lord Beaverbrook commissioned this painting and specified the heart device. The setting of the portrait appears to be the rocky coast of New Brunswick, Canada; the cliffs in the background are lapped by unusually calm waters, a deliberate allusion to the calming effect of this serene and capable woman on the tempestuous Beaverbrook, who saw himself as a raging sea:

On the rock bound coast of New Brunswick the waves break incessantly. Every now and then comes a particularly dangerous wave that breaks viciously into the rock. It is called “The Rage.” That's me.

Beaverbrook: A Study in Power and Frustration (1956).

The painting may be seen as pendant to the 1961 portrait of Beaverbrook by Zinkeisen in the Beaverbrook Art Gallery, New Brunswick.