The adorable nickname Prince Philip’s mum used in loving letters to the Duke revealed – and it will melt your heart

's Hugo Vickers reports, Prince Philip didn't hear from his mother Princess Alice of Battenberg for seven years while he was attending prep school and she was receiving experimental treatment for schizophrenia in Germany.

When he was 16 years old, the publication reports that he was reunited with his mother - and she would write him letters in which she lovingly referred to him as "Bubbikins".

During WWII, Prince Philip - encouraged by his maternal uncle Lord Louis Mountbatten - enrolled in the Royal Navy.

Meanwhile, his mother returned to Athens and ran soup kitchens for the homeless and put her life at risk by hiding her Jewish friend Rachel Cohen and her two children from the Nazis.

Although mother and son lived largely separate lives, Alice - who became a nun after the war ended - frequently wrote loving letters to her son.

Describing how Princess Alice referred to her son as "Bubbikins", the publication reports: "The letters made it plain how proud she was of him."

In one letter, she reportedly wrote: "Congratulations on what you have achieved. My doctor assures me there's not one man in the whole of Germany who is not devoted to you."

What's more, the Princess - who lived in Buckingham Palace for the last two years of her life - also reportedly referred to her daughter-in-law as "Lilibet" like the rest of the Royal Family.

In more Royal Family news, The Queen is ‘touched’ by public’s support since Prince Philip’s death as she sends message ahead of funeral.

And pregnant Meghan Markle will make ‘private arrangements’ to mark Duke of Edinburgh’s life after not being able to attend.

Plus Prince Harry and William won’t stand next to each other at Philip’s funeral with Peter Phillips to separate pair.