William Hague has published his own biographies of William Pitt and William Wilberforce
Ffion Hague has launched a book about the women in World War I Prime Minister David Lloyd George's complicated private life at the Hay Festival.
The Cardiff-born wife of former Conservative leader William Hague said the Welsh Liberal statesman loved women but always put politics first.
She said his wife Margaret Owen was a formidable woman in her own right "and one of the greatest prime minister's wives of modern times."
"She never put a foot wrong," she said.
Raising a huge sum for helping WWI troops, becoming a council leader and the first woman JP in Wales in 1928, Margaret remained "a Criccieth girl at heart".
Mrs Hague, who had access to family papers for her research, said Lloyd George had been a "colourful" and "capable" politician.
But apart from his achievements in war and peacetime as Liberal prime minister and chancellor, he had been a magnet to women right into his late 60s.
As well as his marriage of more than 50 years, The Pain and the Privilege - The Women in Lloyd George's Life deals with his relationships, including his long-term mistress Frances Stevenson, half his age.
With the cover of being his private secretary and with the unspoken collusion of the press, the relationship with Frances remained free of scandal. They were married briefly after Margaret's death.
Mrs Hague said there were many other lovers, and she had received letters from people brought up in orphanages who had been told they were related to him.
Lloyd George represented Caernarfon Boroughs for more than 50 years
Mrs Hague said she had been drawn to the story by her own background as a Welsh-speaker, civil servant and working as a political private secretary to her future husband.
On romance and Mr Hague - the shadow foreign secretary was in the front row - she joked that he once came home and told her he had named a 32-tonne Eddie Stobart lorry after her.
She said having a daffodil later named after her made up for it.
* Meanwhile, Gore Vidal, the veteran American writer, commentator and scourge of George W Bush, was in typically acerbic mood.
The 82-year-old, asked by Sky political editor Adam Boulton if John McCain, as a man in his 70s, might bring maturity as the next US president, replied: "No, senility."
Vidal was in the Barack Obama camp and suggested Hillary Clinton "might get a job in a law firm".
On whether he had any advice to young people, he quipped: "Grow up."