THE symbolic key that was used to open one of Charles Rennie Mackintosh’s masterpieces, the Glasgow School of Art, is to be sold at auction in Edinburgh in April.

The key, which was designed by the famed architect himself, has not been seen in public since the opening ceremony on March 20, 1899, when it was presented to James King, the former Lord Provost of Glasgow.

Following the Lyon & Turnbull auction in April, a donation will be made by both the owner of the key and the auctioneers to The Mackintosh Campus Appeal, helping to restore the building following a fire in 2014.

Mary Newbery, the six-year-old daughter of Fra Newbery, director of the Glasgow School of Art, presented the ceremonial key to King, who then performed the ceremonial unlocking of the door.

The key was passed down through the King family to the current day Sir James King, who hopes its sale will encourage others to contribute to the appeal.

John Mackie, director at Lyon & Turnbull, said: “This remarkable object was designed by the architect of the new school, Charles Rennie Mackintosh.

“As an architect and designer Mackintosh is seen as a ‘key transitional figure from the historicism of the 19th century to the abstraction of the 20th century’.

“With his masterwork, the new Glasgow School of Art of 1899 and 1910 became a building that has come to symbolise his achievement as an architect.”

The minutes of the board of the School of Art describe the events of the day, December 20, 1899, including the moment when Mackintosh’s key opened the building.

“Representatives met in the corporation galleries at 2.30 o’clock – where they were received by the chairman and governors, and having adhibited their names to an illuminated document prepared by Miss Ann Macbeth – a student of the School – were presented to the Hon the Lord Provost Samuel Chisholm. A procession was then formed – walking to the front entrance of the New Building, where a wrought iron key was presented on a white satin cushion by little Miss Mary Newbery to Sir James King Bart. of Campsie who then performed the Ceremony of unlocking the door.”

That account was verified 86 years later by the same girl when she was 80 years old, giving an interview in 1985, and Newbery remembered some of the details the officials had missed.

She said: “Everybody stood out on the steps. Then there was another pause, then I’m afraid there were speeches. I don’t remember what they said I just remember waiting. Then I was shepherded up holding a small, oblong, pale, pearly silk cushion with a silver fringe round.

“This cushion was made by Mrs Mackintosh and my mother. Thinking about this lately, the formal ceremony would be arranged by my father who had a touch of pageantry.

“Then the door was unlocked and in we went. There was a feeling of cheerful achievement.”