When William St. Clair accompanied his cousin William the Conquerer to England, and fought at the Battle of Hastings in 1066, the family joined the many Anglo-Norman generations that would eventually find their way up into Scotland in search of land, power and fortune.
Many generations and almost 400 years later, another Sir William St. Clair endowed the “Collegiate Chapel of St. Mathew” in 1446. It took approximately 40 years to build the section of the chapel you see today as Rosslyn Chapel and it is only a portion of the original design. The initial plans for the Collegiate Chapel of St. Mathew were grand indeed.
The more power and wealth a family had, the more elaborate these structures would be. Sadly, Sir William St. Clair's vision died when he was buried in the unfinished chapel in 1484.
The delicate sculpture, which survived the Scottish Reformation, local vandals and even use by the soldiers of Oliver Cromwell as a stable miraculously survived.
More stained-glass windows were added to the Baptistery in the 20th century to commemorate St. Clair family military service other beloved family members.
It is true that Katherine St. Clair was married to the Grand Master Hughes de Payen and that several Templars fled to Scotland to escape persecution at the beginning of the 14th century.
It is also known that another William St. Clair was a Knight Templar who died in Spain in 1330 trying to bring the heart of Robert the Bruce to the Holy Land. These are facts. The rest is fun speculation for the rest of us!