Born four and a half years apart, Elizabeth and her sister Margaret Rose enjoyed a blissful early childhood at the heart of a loving family. Educated at home, the girls' early lives were closeted and cosy, taken up by riding lessons, card games, tea with cousins, and family pillow-fights. All that was to change when their father suddenly became King in 1936.

Always less conventional and serious than her sibling - both by nature and also because of the lesser responsibilities that awaited her - Margaret was nonetheless deeply loyal to Elizabeth, and missed her sorely when she married, when Margaret was aged 17.

Margaret was far from inactive when it came to royal duties: she undertook her first solo public engagement aged just 15, when she opened a Save the Children play centre in London, and had 50 engagements in her 'coming out' year, when she was 18.

Despite their loving relationship, the more sensible older sister sometimes had issues with her sister's free-spiritedness, mostly famously when Margaret informed her, as Elizabeth prepared for her coronation, that she wished to marry Peter Townsend, a divorced commoner. The Queen was constrained to follow the advice of the prime minister, Winston Churchill, and the Archbishop of Canterbury, who were both adamant such a union could not go ahead.

After her subsequent marriage to photographer Antony Armstrong-Jones ended in divorce, Margaret spent the rest of her life in an apartment in Kensington Palace and never re-married, but instead spent a great deal of time with the Queen and Queen Mother. When she died aged 71 in 2002, after a period marred by ill health, it was her mother and sister who were the most badly affected.

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