She told Elizabeth that it would be surely better if ‘we being two queens so near of kin, neighbours and living in one Isle should be friends and live together like sisters’. And yet, for Elizabeth, Mary was her great rival and although she sympathised with her problems as queen, she was afraid of her power.

Mary has often been seen as a great failure as a monarch – executed, after all, buried in a foreign land. At best, she is seen as a tragic queen. But if we look at her in terms of queenship, she engaged in many acts that Elizabeth was congratulated for – but Mary did the same and lost everything. Elizabeth is famous for her policy of religious tolerance, efforts to listen to ministers from all sides – but Mary too engaged in promoting friendly relations between Catholics and Protestants. Mary, too, surrounded herself with knowledgeable men and created an elegant court and staged lavish court celebrations to ensure loyalty. But she ended condemned as a traitor and Elizabeth lives in memory as Gloriana. In the battle between the two rival queens, Elizabeth seems to be the winner.

Where did Mary go wrong? For me, she was a pawn of others from the beginning. The problems started when she was sent abroad at the age of five, even though she had been crowned queen four years previously. Mary of Guise, mother and Regent to the infant Queen, naturally thought she would be safer abroad, as Henry VIII was attacking Scotland and demanding the baby Queen marry his son. Sending her to France as the future wife of the Dauphin seemed to kill two birds with one stone: Henry VIII couldn’t kidnap the child and Henri, King of France, would send troops to back up the Scots forces against the English.

Mary was surrounded by powerful men on her return to Scotland and did not know who to trust

The little Queen of Scots was still being manipulated. As she approached her marriage, the King began to make secret plans to claim Scotland as his territory if Mary died without heirs. The wedding of fifteen year old Mary and the Dauphin Francis in April 1558 was a grand and glittering affair, with the beautiful young Queen, nearly six foot and clad all in white, but all the symbolism was about France as possessing Scotland, as a husband did a wife. Worst of all, the King began encouraging his new daughter-in-law to stake her claim to the English throne and declare herself and her husband as King and Queen of France, Scotland and England. His basis, of course, was that Elizabeth, the heir in waiting, was illegitimate, born of a heretic mother. There was nothing that would infuriate Elizabeth more.

In the winter after Mary’s wedding, Elizabeth became queen on the death of her half-sister, Mary I. She claimed it was the ‘doing of the Lord and marvellous’. At her grand Coronation, she played the role of the Great Queen, all powerful, all conquering.

But the armour of the all-powerful queen had a chink – and that was Mary, Queen of Scots. Her advisors were always afraid that she would be seen by Catholic Europe as the one true Queen and that they would depose Elizabeth for her. But, Elizabeth told them, Mary, was safely in France.

In 1560, Francis died and Mary, no longer wanted at court, returned to Scotland – to be its eighteen year old Queen. Unlike Elizabeth, who had spent her time waiting for the throne gathering loyal men around her, watching and understanding the politics of the country she would rule, Mary barely knew her country, preferred to speak French and did not know who to trust. Although the public welcomed her, the lords around her – including her half brother, James Stuart (son of her father and his mistress) – suspected she might deprive them of power and lands. Almost immediately, the coup attempts began.

Surrounded by often hostile men, Mary was keen to build a relationship with Elizabeth, her ‘neighbour’ and ‘sister’. Elizabeth sent supportive words and talked of a meeting, but it never quite happened – much to the relief of her advisors.

In 1565, Mary married Lord Darnley, handsome, aristocratic, charming and entirely corrupt. The marriage was a failure. When Darnley and a collection of conspirators stabbed Mary’s secretary, David Rizzio, in front of her, it was understandably the last straw. And then on the morning of 10 February, all Edinburgh was rocked by an explosion. The house in which Darnley had been staying had been blown up – and he and his servant were nearby. They had been murdered and all Europe was scandalised. Elizabeth wrote to Mary begging her to find the men responsible, suggesting the Scots queen was ‘looking through her fingers’ while the guilty escaped. Others thought the same – and the lords saw their chance to rid themselves of Mary once and for all. She fought back, was captured and escaped – and thought that her beloved dear ‘neighbour’ would help her. Mary made the fatal error of rushing to England in the hope of Elizabeth’s help. But instead she found herself imprisoned for eighteen years in England, and finally exposed as conspiring against the Queen and executed for treason.

Two women struggled with each other in a male dominated world. They could not escape their bond. Mary failed at becoming Queen – but her story shows how near impossible it was for a woman to rule at the time. Whatever she did was damned. And still now, women’s rule is criticised in ways that men’s is not; they are characterised with stereotypes. Mary, Queen of Scots shows us how difficult it was to be a female leader, how hard it is to shake off the conventions by which femininity is seen. It’s still not easy today.

• Rival Queens by Kate Williams is published by Hutchison. Hardback and eBook, £25.

Kate Williams: How Mary, Queen of Scots was betrayed