Andrew Morton: Elizabeth & Margaret

They were the closest of sisters and the best of friends. But when, in a quixotic twist of fate, their uncle Edward VIII decided to abdicate the throne, the dynamic between Elizabeth and Margaret was dramatically altered. Forever more, Margaret would have to curtsey to the sister she called 'Lillibet'.

And bow to her wishes. Elizabeth would always look upon her younger sister's antics with a kind of stoical amusement but Margaret's struggle to find a place and position inside the royal system - and her fraught relationship with its expectations - was often a source of tension. Famously, the Queen had to inform Margaret that the Church and government would not countenance her marrying a divorcee, Group Captain Peter Townsend, forcing Margaret to choose between keeping her title and royal allowances or her divorcee lover.