Katherine was born on 4 May 1913 in the Royal Palace in Athens, a few weeks after her paternal grandfather, King George I of Greece, was assassinated in Thessaloniki.

In 1941, after Greece had been overrun by Axis forces, she fled to South Africa with her third brother, Paul, in a Sunderland flying boat, where she worked as a nurse at a hospital in Cape Town.

On board, she met Major Richard Campbell Brandram MC (5 August 1911 – 5 April 1994), an officer in the British Royal Artillery.

[3] On 1 April at the Royal Palace, three weeks prior to the wedding, her brother King George had a stroke and died shortly after in Katherine's presence.

[4][5] George was succeeded on the Greek throne by Katherine's third brother Paul, who acted as best man at the wedding, which took place according to schedule on 21 April 1947.

According to her obituary in The Daily Telegraph, "Lady Katherine lived quietly but remained in close touch with her own and the British royal families.

Her death marked the end of all female-line direct descendants of Frederick III, German Emperor and Victoria, Princess Royal.