A businessman from Stirlingshire has been confirmed as a direct descendant of a medieval Scottish king.

A DNA sample provided by Archie Shaw Stewart confirmed that he was in the family line of King Robert III, who ruled Scotland from 1390 until his death in 1406.

Mr Shaw Stewart, who runs an electronics firm based near Doune, had already conducted his own research, which showed that he was related to one of the king's sons, Sir John Stewart of Blackhall and Ardgowan.

His family line also includes Sir John's great-grandfather, Walter Stewart, one of Robert the Bruce's main commanders at the Battle of Bannockburn in 1314.

In addition to uncovering Mr Shaw Stewart's family connection, the organisers of the study also revealed that he holds a distinctive 'genetic marker' which had not been found in Robert III's brothers. This leads to the potential discovery of future descendants who carry this marker and can be directly linked to the former Scottish king.

The study was carried out by the genealogical studies postgraduate programme based at the University of Strathclyde, alongside the Bannockburn Family History Project, which attempts to uncover connections between people living today and ancestors who fought in the battle.

Mr Shaw Stewart said: "My great uncle, Patrick Shaw Stewart, produced an extensive family tree over 100 years ago, extending back to Robert III. He would be very satisfied to see this part of it - Stewart - verified by new technology."

Graham Holton, principal tutor at the Genealogical Studies Postgraduate Programme, said: "This is a fascinating discovery of a distinct marker for descendants of Robert III.