Mrs Seton laughed in agreement.

Four husbands! thought the Queen of Scots. And the first three dying in so convenient a manner! – just when the farmer's daughter had grown into her new rank and might be wishing for a greater. The Queen of Scots's husbands had never consulted her convenience in their dying. Her first, the King of France, had died at the age of sixteen and so she had lost the French throne – a circumstance that had caused her great pain. Her second husband (whom she had hated and wished dead) had fallen ill in the most tantalising way, but had utterly failed to die – until some kind person had first blown him up and then strangled him.

This suggested an idea to the Queen of Scots. "Did the Countess's husbands all die naturally?" she asked.

Mrs Seton snorted in ridicule and leant closer. "Her first husband was no more than a boy! The Countess – who was only plain Bess Hardwick then – embroidered him a coat all chequered over with black and white squares. And, after he had worn it a few times, he began to complain that the whole world had become to him nothing but black and white squares. Every dark tabletop seemed to him a gaping black hole that meant to swallow him up and every window filled with white winter light was ghostly to him and full of malicious intent. And so he died, raving about it."

The Queen of Scots was impressed. She had heard of a poisonous dart sewn into a bodice to pierce the flesh, but she had never heard of anyone being killed by embroidery before. She herself was very fond of embroidery.

She remembered how she had fancied herself a mouse in Elizabeth 's skirts. A needle, she thought, was a most suitable weapon for a mouse – mouse-sized, in fact. And if Elizabeth were to die of that needle (or indeed of anything else) then the Queen of Scots would surely be Queen of the English too.

Tutbury Castle was cold and evil-smelling. It was also rather small and so they did not have to walk far before they found the Countess, seated at her needlework.

The Queen asked the Countess what she was embroidering.

"A picture of a beautiful palace in a sweet country," said the Countess and showed the Queen. "As I sew I like to fancy that my children and grandchildren will one day live in houses such as this. It is a foolish idea, no doubt, but it passes the time pleasantly."

The Queen of Scots rolled her eyes at Mrs Seton to express her astonishment at the presumption of the farmer's daughter.

The Countess saw what the Queen did but she was not in the least abashed.

Then the Queen of Scots began to talk of embroidery, and of husbands, and of the death of husbands; and just for good measure she threw in a few references to black and white chequering.

The Countess replied blandly that embroidery was a very charming way to pass the time, and husbands were generally a good thing, and their death much to be regretted.

The Queen frowned. She had heard that the Countess was a very clever woman. Surely she must understand what was meant?

The Queen said, "I should like to send a present to my dear sister, the Queen of England. A piece of embroidery that I intend to work with my own hands. The work will be nothing but a pleasure to me for I declare that I love the Queen of England better than anyone else in the world."

"As everyone must who sees her," agreed the Countess piously.

"Quite," said the Queen of Scots and then she began to speak of how great Princes rewarded those who helped them.

The Countess looked neither excited nor fearful at these hints and insinuations of future greatness. She gazed calmly back at the Queen.

The Queen brought out a book filled with quaint pictures which might be adapted for needlework. There were cockatrices and lions and manticores – all sorts of beasts which (the Queen hoped) might be made to tear Elizabeth to pieces through the means of magic and embroidery.

The Countess dutifully admired the pictures, but offered no opinion as to which the Queen should choose.

Henceforth every morning the Queen, the Countess and Mrs Seton sat down to embroider together. Gathered in the light of the window with their heads bent over their work, they grew very friendly. The Queen embroidered a pair of gloves for Elizabeth, which she decorated with pictures of sea monsters amid blue and silver waves. But though she filled the monsters' mouths with sharp-looking teeth, Elizabeth was not bitten by anything; nor did she drown.

The Earl of Shrewsbury sent a letter to Queen Elizabeth saying that the Scottish Queen passed her time very innocently. This was not in the least true: when she was not at her needlework, she was secretly intriguing with English malcontents who wanted to assassinate Elizabeth and she also wrote letters to the Kings of Spain and France cordially inviting them to invade England. But she did not forget to admire the Countess's needlework and to talk, every now and then, of black and white chequering.

But the years went by; Elizabeth was as healthy as ever, no one invaded and the Queen grew tired of paying the Countess compliments. She said to Mrs Seton, "She is obstinate, but I have magic of my own. And if she will not help me then I will use it against her. After all I know what it is that she loves the best."

Then the Queen combed and dressed her red-brown hair. She put on a gown of violet-brown velvet embroidered with silver and pearls. She called the Earl to her chamber and made him sit at her side and smiled at him and told him that of all the gentlemen who attended her, it was he whom she trusted the most. Day after day she made him many sweet speeches, until the poor old gentleman did not know whether he was on his head or his heels and was very near falling in love with her.

Mrs Seton watched all this with a puzzled air. "But I do not think it is the Earl that the Countess loves the best," she said to the Queen.

"The Earl!" The Queen burst out laughing. "No, indeed! Whoever said it was? But she loves his money and his lands. She desires that they shall be given to her children and grandchildren. It is all she ever thinks of."

Word reached the Countess of what was happening, as the Queen knew it must, but no sign of anger appeared on her broad Derbyshire face. The next time that the three ladies were seated at their embroidery, the Queen revived the old question of what present would please the Queen of England best.

"A skirt," said the Countess of Shrewsbury in the most decisive manner. "A skirt of white satin. Her Majesty loves new clothes."

The Queen of Scots smiled. "As do we all. And what shall the devices be?"

"Let it be powdered with little pink carnations," said the Countess.

"Little pink carnations?" said the Queen of Scots. "Yes," said the Countess.

So somewhat doubtfully (for she would have much preferred poisonous snakes and spiders) the Queen of Scots embroidered a skirt of white satin with little pink carnations; and sent it to the Queen of England. Not many weeks later she heard that Elizabeth had got the pox. Her white skin was all over pink pustules!

The Queen of Scots clapped her hands together in delight. Over the next week or so she drew up a list of the great lords and bishops of England. She cast her mind back over the years of her imprisonment, recalling past slights and kindnesses, considering who should live and be rewarded, and who should be sent to the Tower and die.

Then a day came when the wind blew and the rain lashed the glass, and the Countess entered the Queen's room unannounced. Her eyes were bright with excitement. She brought news, she said. Queen Elizabeth's advisers and councilmen had been put into a great fright by Her Majesty's illness and what had terrified them most of all was the thought that the Queen of Scots might become Queen of England. "For," said the Countess heartlessly, "they hate you very much and dread the havoc you would certainly bring upon this realm. And so they have passed a law saying you shall never be Queen of England! They have dismissed you from the line of succession!"