The contents of the Gwydir Family History
The 'History' is the result of research by Sir John using a combination of history books and official sources. Also, he relied on his close links with bards, antiquarians and scholars. Sir John starts by recounting the history of his ancestors from the middle of the twelfth century starting with the family of Owain Gwynedd. He claims that his family is descended from Owain's second son, Rhodri. The 'History's' main theme from then on centres around the trials and tribulations of the family of one of Rhodri's descendants, Hywel ap Dafydd, during the tempestuous years of the late Middle Ages. He looks at how the family flourished during this period despite social and economic problems and went on to establish itself at Gwydir.
Because of the scarcity of documents on Welsh history from the beginning of the early modern period it is a very important source. Despite this, it is not completely reliable. Sometimes, when there was a gap in the history, Sir John used his imagination to fill it. Also, it contains a number of stories and traditions that are not supported by any historical evidence.