Elizabeth was born at 02:40 (GMT) on 21 April 1926, during the reign of her paternal grandfather, King George V. Her father, Prince Albert, Duke of York (later King George VI), was the second son of the King. Her mother, Elizabeth, Duchess of York (later Queen Elizabeth), was the youngest daughter of Scottish aristocrat Claude Bowes-Lyon, 14th Earl of Strathmore and Kinghorne. She was delivered by Caesarean section at her maternal grandfather's London house: 17 Bruton Street, Mayfair. She was baptised by the Anglican Archbishop of York, Cosmo Gordon Lang, in the private chapel of Buckingham Palace on 29 May,[c] and named Elizabeth after her mother, Alexandra after George V's mother, who had died six months earlier, and Mary after her paternal grandmother. Called "Lilibet" by her close family, based on what she called herself at first, she was cherished by her grandfather George V, and during his serious illness in 1929 her regular visits were credited in the popular press and by later biographers with raising his spirits and aiding his recovery.

During whose reign was Elizabeth born?