A family's battle to claim part of an inheritance believed to be worth half a billion pounds has been chronicled in a new book.

Titled 'Inheritance: The fight to win an aristocratic birthright and a half-billion-pound trust fund', the book centres around the Fletcher family of East Lothian, who claim descent from Robert the Bruce.

Still well known in Scotland to this day, the Fletcher lineage also includes Andrew, who opposed the 1707 Act of Union which saw his country's parliament join with England's.

While the family's pedigree has never been in doubt, what is is whether deceased Swansea factory worker Ken Matthews was the son of Jock Fletcher.

In 1933 Mr Fletcher inherited the vast Emily Charlotte Talbot trust fund which is today estimated at a value in excess of £500 million pounds and is part of an estate that includes Copped Hall in Epping.

Written by retired lawyer and best-selling author John Morris with the help of Mr Matthews' wife Penny, 'Inheritance' argues Mr Fletcher was related to the factory worker and that his descendants are now due part of the fortune.

Mr Morris explained: "Penny and I met in about February 2018, she introduced me to some witnesses and I got started right away.

"I conducted six months research before starting to write. By then I was convinced that Ken Mathews was Jock Fletcher’s son.

"It is not strictly necessary to have DNA to prove a paternity case, but it certainly helps.

"Even without DNA, by 1998, the Mathewses had, in my opinion, amassed sufficient evidence to prove their case several times over."

According to Mr Morris the case was thrown out after it was filed under the wrong act, leading the Matthew's family to set about gathering DNA evidence.

Now they are in possession of what they believe is Mr Fletcher's DNA, the family is waiting on laboratory tests to be returned confirming or disproving their lineage suspicions.

If they come out positive, a legal process can be triggered which may result in Mr Fletcher's body being exhumed for further analysis.

For the Matthews family however, evidence of their heritage is wound up in their family history.

According to witnesses accounts and Statutory Declarations provided by Margam Estate workers, they were told Mr Matthews was the lovechild of Margam housemaid Ivy Pinn and laird of the manor Mr Fletcher.

It is rumoured the couple enjoyed a 12-year love affair from the mid-1920s, which survived Mr Fletcher’s short marriage to socialite Norah Gabbett-Mulhallen.

Reportedly their relationship ended in 1936 when Ms Pinn fell pregnant, leaving Mr Matthews to be scooped out of a workhouse by a childless couple living in a South Wales village.

He spent the last twenty one years of his life trying to prove that Mr Fletcher was his father; not just to inherit his huge estate, but to learn if a mystery life-threatening illness was hereditary.

'Inheritance: The fight to win an aristocratic birthright' will be published later this year.

The Fletcher family's lawyers Mills & Reeve LLP declined to comment on their behalf.