MARY Queen of Scots spent the last night of her life lying wide awake through the early hours of February 8, 1587, at Fotheringhay Castle on the flat plains of Middle England, 250 miles south of the rugged Scottish border.

Born in 1542, Mary had been in English captivity since 1568. She fled her homeland after losing the Battle of Langside, outside Glasgow, to her half-brother, James Stewart, Earl of Moray and Regent of Scotland on behalf of her son, the infant King James VI. It was also a victory of their Protestantism over her Catholicism.

Finally escaping Scotland in a boat across the Solway Firth, Mary made her way into England in the hope of help from her 35-year-old cousin, Queen Elizabeth – who did offer asylum but nothing else. She lodged Mary in one remote castle after another while pondering a final fate for her. Her indecision – and Mary’s incarceration – lasted 19 years.

In London the government’s “Spymaster General”, Sir Francis Walsingham, urged Elizabeth to get rid of her unwelcome guest by hook or by crook. But the English monarch had her reservations. She believed royalty was a divine institution, not something to be snuffed out at a political whim. Mary was, after all, Elizabeth’s own legal heir and next in line to her throne. If subjects gained the power of life and death over sovereigns, where would it all end?

Mary had no such qualms. As a plausible heir to the English crown, she cheerfully plotted to seize it. To her the details of descent mattered less than the legitimacy of her claim, itself a guarantee of social order. She was in some sense an equal of Elizabeth. Neither woman thought mere commoners had a right to deal with her affairs. Though deposed and detained in England, Mary was always treated as a queen. She appointed the keepers to her own court, corresponded freely and received guests. This was more house arrest than imprisonment.

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Her aim was to preserve her own status in a royal court, with dozens of servants and all the rest of royal paraphernalia.

Elizabeth had at first welcomed the escape of a fellow queen, while scheming to use it to her own advantage. Her standing with European powers, perhaps even within the British Isles, would suffer should she seem to sanction rebellion.

The National: Queen ElizabethQueen Elizabeth

Yet Regent Moray was Elizabeth’s most reliable ally. If Mary finally toppled him, she would damage English interests, too. Another Elizabethan politician, Robert Cecil, said Mary should just be sent back to Scotland. The two governments discussed a range of possibilities, but the Scots said they didn’t want Mary.

For Elizabeth it was vital to hang on to the initiative. Once it became clear she would neither restore the Queen of Scots nor let her wander off to make trouble in Europe, Mary had two courses of action open to her, one of which was to make peace with the ruling classes across the British Isles, on an agenda of stability, legitimacy and links with other Protestant monarchies – implying also that she was no longer intent on being an agent of Rome.

Mary’s most serious effort to renew Protestant friendships came in the period 1581-4, in a scheme that would have freed her and restored her to a nominal joint sovereignty with her son. She offered to live in England and resign the executive government to him.

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Or else, Mary could have become actively hostile to Elizabeth, exploiting her own Catholicism and claim to the English throne. She would have needed to link up with the militant movement of the Counter-Reformation, especially with Spain, the European power keenest to oust Elizabeth.

Mary spent more time plotting than anything else. It became her main political activity. She knew she was playing for high stakes. If the risks were great, so might the benefits be. She still thought those risks worthwhile. They finally went over the top.

Anthony Babington, a Catholic landowner, hatched a plot to assassinate Elizabeth, not just depose, imprison or expel her. Even Catholics who knew about the plot could not agree with him. Mary had been informed, and was among the few who thought killing a Protestant ruler could be justified: she did it herself, after all, to one of her consorts. Now her cover was blown, and those round Elizabeth who had conspired to eliminate her rival found themselves triumphantly vindicated.

The National: Mary Queen of ScotsMary Queen of Scots

In 1586 Mary was put on trial for treason at Fotheringhay. She mounted a spirited defence, asking how she could commit treason against a woman who was not her sovereign. But there was little doubt she would be convicted.

Even then Elizabeth hesitated to have the sentence of death carried out. She kept everybody on tenterhooks through a long winter. At length came the morning of February 8, 1587. Mary was kept awake all night by the noise of a scaffold being built in the great hall of Fotheringhay. After dawn a calm, courageous and still majestic queen made her way to the place of execution. She was dressed almost entirely in black with a long white veil, and carried a crucifix and prayer-book.

An assemblage of spectators awaited her. A stage had been erected about 12ft square and 2ft off the ground. There were two stools for Mary’s custodians, George Talbot, Earl of Shrewsbury, and Henry Grey, Earl of Kent, with another for the queen to sit on while she was being disrobed.

As was the rather gruesome custom, the two executioners made a formal request for her forgiveness. She answered: “I forgive you with all my heart, for now I hope you should make an end of all my troubles.”

Her ladies removed her black robe and left her standing in a dress of crimson velvet that she chose for being the colour of blood and a symbol of martyrdom in the Catholic Church. She had planned this moment of drama for the last scene of her life.

After blindfolding Mary, her ladies left the stage. She refused the ministrations of an English clergyman and, kneeling down on her stool, prayed aloud in Latin without a tremor of fear in her voice.

Groping for the block, she laid her head on it, holding her chin in position with both hands. Two strokes of the axe were needed to decapitate her. The executioner raised her skull and cried: “God save the queen.”

There was a last surprise. Mary had been wearing an auburn wig, from which her skull suddenly dropped away to reveal the reality of an old, grey-haired woman, now suffering no more.

Her lips stirred up and down for a quarter-of-an-hour after her head was cut off.