The book "Aethelflida: The Ladybird Expert Book. The Forgotten Founder of England" tells about the fascinating life and activities of Aethelflida, the daughter of the Anglo-Saxon king and sister of King Alfred the Great. She was a warrior, politician and diplomat who played an important role in the formation and defense of the Anglo-Saxon kingdom of Mercia in the Middle Ages. This book contains information about the life of Aethelflida, her military exploits and contribution to the development of the Anglo-Saxon state. The author examines in detail the historical sources and archaeological finds related to Æthelflida, revealing unknown facts about this prominent figure of medieval Europe. Aethelflid: The Ladybird Expert Book is a fascinating source of knowledge for those interested in the history of medieval England and the notable figures of the period.