DEEP in an archive, more than two dozen letters written by Mary, Queen of Scots, lie largely unseen for centuries.
Many are written in a secret code as Mary fought to preserve and protect the Catholic faith in Scotland after the 1560 Reformation which saw the country break with Rome.
But soon the letters, which in recent years have only been seen by a select group of historians, will be available to view on-line.
Visitors to the Scottish Catholic Archives website will be able to examine the letters, which also contain details of Mary's power struggle with her Protestant cousin, Queen Elizabeth, who was on the throne in England. The struggle eventually led to Mary's execution in 1587.
Most of the documents are diplomatic letters exchanged between Mary and Archbishop Beaton, who became her ambassador to France.
He was her "eyes and ears" in Paris after her return to Scotland on the death of her first husband, Francis.
The letters, written in French and often penned by her staff but signed by Mary, also express her concerns over the growing political turmoil in Scotland in the wake of the Reformation, which led to the celebration of Mass being declared illegal.
The letters are part of a treasure trove of 250,000 items on the origins and history of the Catholic Church in Scotland.
Andrew Nicoll, keeper of the huge collection of the Scottish Catholic Archives, has spent the past six years transferring handwritten records from 180 binders into a vast electronic library which should be ready by mid-summer.
The archive, based in Edinburgh since 1958, contains the largest body of material relating to the Catholic Church anywhere in the UK and one of the most comprehensive outside the Vatican.
Viewers will be able to browse through records of everything from the historic archives of individual churches around Scotland to collections devoted to landmark occasions such as Pope John Paul II's visit in the early 1980s.
The archive includes detailed accounts of how the Catholic cause in Scotland was kept alive in the wake of the Reformation and how the modern church was shaped in the 19th century after full civil rights for Catholics were restored in 1829.
The records also contain accounts of how young Scots travelled across Europe in the 19th century to train for the priesthood; some of the earliest written records of Australia; and insights into the lives of 18th-century Scots who had migrated to Nova Scotia in Canada.
Extensive files are also held on the writer Oscar Wilde; the many mysterious sightings of the Loch Ness Monster; how anti-Catholic riots flared in Edinburgh's normally peaceful Morningside suburb less than 80 years ago; and the story of how a priest helped get Hibernian Football Club off the ground.
Mr Nicoll said: "Much of the current collection was brought here by Father William James Anderson, the first keeper of the collection, down from Blairs Seminary, in Aberdeenshire.
"The idea at the time was to make it easier for researchers and historians and bring the collection close to others held by the National Archives and National Library in Edinburgh.
"By the summer, there should be details online of everything that's held in the collection – from the 12th century right up to the start of the 20th century."
Hidden gems to be unveiled from ancient collection
HIGHLIGHTS from the Scottish Catholic Archives:
• Official documents relating to the origins of Hibernian Football Club. It was formed in 1875 by the Catholic Young Men's Society attached to St Patrick's Church in the Cowgate. Some of the club's members had approached the priest Father Edward Hannan with the idea of setting up a team, initially based at the YMCA hall in nearby St Mary's Street.
• An official archive devoted to Pope John Paul's celebrated visit to Scotland in 1982. It lasted barely 36 hours, but included a Mass in Glasgow's Bellahouston Park attended by some 300,000 people, a youth festival at Murrayfield Stadium, in Edinburgh, and an historic meeting with the moderator of the General Assembly of the Church of Scotland.
• Records dating back to 1742 of Fort Augustus, the famous abbey on the banks of Loch Ness, showing how the monks were gripped by the early days of "Nessie Fever". They were so intrigued by the riddle of the Loch Ness Monster in the 1920s that they kept their own archive of newspaper cuttings charting sightings of the "creature".
• The story of John Ogilvie, the 16th-century martyr who was tortured and hanged in Glasgow, but became Scotland's only saint in 1976 after a long campaign to have him canonised.
In 1967, John Fagan, a Glasgow docker, was dying from terminal cancer and his family and parish priest prayed to Ogilvie. The cancer later disappeared in a manner that could not be explained by the medical establishment.
• Documents detailing the notorious anti-Catholic riots in Edinburgh's Morningside area in June 1935. Buses carrying Catholics were stoned and jeered by a crowd of up to 10,000 during a demonstration against a Roman Catholic Religious Congress. It had been organised by the Protestant Action Society and led by John Cormack, a city councillor.
• More than two dozen letters written by Mary Queen of Scots, Scotland's last Catholic Queen, some in her own hand and some in a secret cipher.
Originally held by the Scots College, in Paris, until the French Revolution in 1790 when the college and other institutions associated with the papacy were suppressed and threatened with destruction.