Princess Mary, who was born on this day in 1897, was at the centre of the major royal plot following the announcement of the late King Edward VIII's abdication - later the Duke of Windsor - in 1936. Mary was one of several members of the Royal Family who voiced their concern and even plotted to convince her elder brother not to marry twice-divorced American, Wallis Simpson.

One of the letters found casts a light on a conversation between her and Loelia, Duchess of Westminster, who urged the princess to use her influence over her eldest brother to “get rid” of Wallis. In the letter, Loelia told Mary: "You can’t drive him, but you may be able to lead him.

"You used to be such good chums in your school days. Sympathy and kindness may do a lot for him now."

She continued: "It may be a turning point in his life and perhaps get rid of her for good." Politicians also spoke against the potential marriage between Edward and Wallis.

The then-Prime Minister, Stanley Baldwin, warned the King that the people of Britain would never accept "that woman" as Queen Consort.

Princess Mary is remembered for her hard-working attitude and devotion to royal service, with many historians comparing her to her great-niece, Princess Anne.

Another connection Princess Mary shares with the current Princess Royal is the fact that in many pictures, she is the spitting image of Princess Anne's daughter, Zara Tindall.

Princess Anne's only daughter, who married Mike Tindall in 2011, was born in May 1981 - 16 years after Mary's death in 1965.

Unlike Mary, Zara famously doesn't carry a royal title as it is thought that Anne declined the Queen's offer so her children could be raised as normally as possible.

However, like mother-of-three Zara, Mary was a mother of two sons, George and Gerald Lascelles.