During a dramatic thunderstorm on the night of 21st August 1930 at Glamis Castle, a second daughter was born to T.R.H. The Duke and Duchess of York, the future H.M. King George VI and H.M. Queen Elizabeth. This marked the last royal birth in Britain to be witnessed by a Minister for the Crown and placed the child fourth in line to the throne; more significantly, the Princess was sister to the future Queen. After much deliberation, the baby was named Margaret Rose of York, carrying associations with Saint Margaret, the 11th century Scottish Queen and the symbolism of the House of York. Furthermore, the Duchess of York herself had 'Marguerite' as a middle name, while one of Margaret's godparents, her mother's sister, Lady Granville, was called 'Rose'.

Yet the decision had not been immediate. After several weeks the Duchess wrote to H.M. Queen Mary, 'I am very anxious to call her Ann Margaret as I think that Ann of York sounds pretty, and Elizabeth and Ann go so well together. I wonder what you think?'. H.M. King George V, however, had objected to the name Ann, and since the King's say in the matter was final, the couple bowed to his wishes. In the following letter to her mother-in-law, the Duchess wrote that 'Bertie and I have decided now to call our little daughter 'Margaret Rose', instead of Margaret Ann, as Papa does not like Ann. I hope that you like it. I think that it is very pretty together.'