Simon Winchcombe Henry Howard Hartley saw the Prime Minister for the first time that morning, and his father for the last time that night. It happened thus: For the past 200 years, the Hartley family had either taken holy orders, ending their days as bishops, or entered the House of Commons, before joining the Cabinet as a minister of the Crown.

Simon’s father, the Rt Hon. John Hartley PC KBE MC, was no exception and ended a distinguished career as Home Secretary before being elevated to the upper house as Lord Hartley of Bucklebury. His wife Sybil was first and foremost a housewife and a mother, who occasionally involved herself in good works, which was no more than was expected of a Hartley spouse. So, when Sybil delivered a son, Simon – all Hartley children were named after disciples – they both assumed he would follow in the family tradition and either become a bishop or a Cabinet minister.

Had he done so, this tale would never have been written.

Their only child, Simon Hartley, showed from an early age that he had no interest in the family tradition, when at the age of eleven he won a scholarship to the North London Grammar School, despite having been offered a place at Harrow, the family alma mater. And on leaving school, he progressed to King’s College London to study law, rather than going up to King’s College Cambridge to read divinity or politics.

When Simon graduated three years later, he bucked another Hartley trend by becoming the first member of the family to be awarded a first-class honours degree, rather than the usual second or even the occasional third. And, if that wasn’t enough, after leaving university Simon migrated to Boston to join a bunch of colonials at somewhere called the Harvard Business School, an establishment his father wasn’t sure he approved of.

Two years later, as a graduate of the other Cambridge, Simon returned to his native soil to be offered a dozen jobs in the City of London, ending up as a trainee at Kestrals Bank with a starting salary well in excess of anything his father had earned as a minister of the Crown.

During the next decade, he rarely left the square mile, other than to travel to distant lands, where he would negotiate deals that left his colleagues in awe, while making a fortune for his bank.

By the age of 40, Simon had married a beautiful and talented woman, Hannah, who had borne him two sons, Robert and Christopher – neither disciples – and had joined the board of Kestrals as the company’s youngest director. It was assumed it could only be a matter of time before he would become chairman of the bank. And, indeed, he might have done, had he not received a call from Number 10 Downing Street asking if he would be kind enough to join the Prime Minister to discuss a matter of national importance.

By the time Simon left the Prime Minister’s residence, he’d promised Mr Blair he would consider his proposal and let him know his decision by the end of the week.

Once Simon was back on Whitehall, he hailed a cab that took him to Paddington, well in time to catch a train to his family home in Berkshire.

During the journey to Bucklebury, he reflected on the Prime Minister’s offer and how his family might react to the news. His father would tell him he had no choice, repeating words such as “honour”, “duty” and “self- sacrifice”.

He couldn’t be sure how Hannah would respond, although he was in no doubt his two teenage sons would express their firmly held opinions on human rights – or the lack of them – in Saudi Arabia, especially when it came to women.

Hannah was waiting for Simon outside the station, a sad and forlorn look on her face.

He kissed her on the cheek before climbing into the passenger seat of their car and immediately asking: “How’s Father?”

“No better, I’m afraid,” she replied, as she switched on the engine and eased the Mini out of the car park and onto the main road. “Your mother spoke to the doctor this morning, and he’s saying it can only be a matter of weeks, possibly days before…”

Both of them fell silent as Hannah drove onto a quiet country lane surrounded by acres of green fields with little groups of sheep huddled in corners, suggesting rain.

“I know he’s looking forward to seeing you,” said Hannah, breaking the silence. “He was saying earlier that there are a couple of family matters he needs to discuss with you.”

Simon knew exactly what his father had in mind, painfully aware one of them couldn’t be avoided any longer. After a couple more miles, Hannah turned off the main road, lowered her speed and proceeded slowly down the long drive that led to Hartley Hall, a home the family had lived in since 1562.

As Hannah brought the car to a halt, the front door opened and Lady Hartley appeared on the doorstep. She came down the steps to greet them, giving her only son a warm hug, while whispering in his ear: “I know your father wants to see you, so why don’t you go up and join him while I give the rest of the family some tea?”

Simon walked into the house and proceeded slowly up the stairs. When he reached the landing, he stopped to admire an oil painting of his distinguished ancestor, the Rt Hon. David Hartley MP, before knocking quietly on the bedroom door.

It had only been a few days since his last visit, but his father had visibly worsened. Simon hardly recognized the frail figure with thinning hair and a sallow complexion, who was propped up in bed, his head resting against two pillows. Breathing heavily, he held out a bony hand, which Simon held onto, as he sat down on the bed next to him.

“So why did the Prime Minister want to see you?” were his father’s opening words, before he’d even said hello to his son.

“He’s invited me to lead a British delegation to Saudi Arabia in order to negotiate a major arms deal.”

His father couldn’t hide his surprise. “That won’t be greeted with overwhelming acclamation,” he suggested, “not least by the Prime Minister’s colleagues on the left of his party, who keep reminding us that the Saudis continue to outlaw trade unions.”

“Possibly,” said Simon. “However, if we could land the contract, those same trade unions would welcome the thousands of jobs that would suddenly become available up and down the country.”

“Not to mention the millions that would start flowing into the Treasury.”

“Billions,” said Simon, “and Blair didn’t stop reminding me that if we don’t get the contract, the French will.”

“Reason enough for you to accept this assignment, my boy,” said his father, “and as you are bound to be away for several weeks, possibly months, there are one or two matters we need to discuss before you go.

“The old order changeth, yielding place to new,” the old man continued, quoting his favourite poet, “so I can only hope that in time you will come and live in Hartley Hall and take care of your mother. ’Tis the natural order of things.”

“You have my word on it,” promised Simon.

“And I don’t want your mother worrying about financial matters. She still tips waiters a shilling and considers it extravagant.”

“Fear not, Father,” said Simon. ‘“’ve already set up a trust fund in her name, which I’ll personally administer on her behalf, so she won’t have to fuss about any temporary financial difficulties.”

“And then there’s the important issue,” said his father, “of what you should do with Jefferson’s Declaration of Independence which, as you know, has been in our family for over two hundred years. We should have carried out the President’s wishes long before now. With that in mind, I made an appointment to see the American Ambassador in order to hand over the Fair Copy along with the letter that shows the great man had always intended it to be bequeathed to the American people.”

“‘In the fullness of time’,” Simon reminded him.

“To be fair,” said the old man, “it hadn’t occurred to me that it was of any value other than as an historic memento, until I read recently that one of Benjamin Franklin’s printed copies of the Declaration sold for over a million dollars, which is when I felt concerned for the first time.”

“No need to feel concern, Father. Once the negotiations for the arms deal have been completed, the first thing I’ll do when I get home is visit the American Embassy and hand the Declaration over to the Ambassador in your name.”

“Along with the letter expressing Jefferson’s wish that it should be given to Congress, which will remind people that our family played their part in a footnote of history. However, the other five letters should remain in the family archives and must be passed on to your firstborn, who I do believe I can hear heading towards us – either that or it’s a pack of wolfhounds that are about to appear.”

Simon smiled, glad to see that his father hadn’t lost his sense of humour. He climbed off the bed and opened the door to allow the rest of the family to join them.

Robert was the first to greet his grandfather, but even before he reached his bedside, the old man said: “Robert, I need to be sure you can repeat the words Thomas Jefferson wrote to your great ancestor over 200 years ago.”

Robert grinned, looking rather pleased with himself. He stood up straight and began, “Dear Mr Hartley.”

“Date and address,” demanded the old man.

“Hôtel de Langeac, Paris, August 11th, 1787.”

“Carry on,” said his grandfather.

“I hope you will grant me your permission to impose upon your time by allowing me to send you my Fair Copy of the Declaration of Independence, which I earlier delivered to Congress for their consideration. You will see that it includes the two clauses you and I discussed in London, namely the abolition of slavery and our future relationship with King George III once we become an independent nation. Copies were made by my friend and colleague Benjamin Franklin and distributed among interested parties. Much to my dismay, when members of Congress divided, both clauses were rejected. However, I would not want you to think I had not taken to heart your wise and sound counsel and tried to convince my fellow congressmen of the merit of your judgement.

“Once you have had a proper chance to peruse the Fair Copy at your leisure, perhaps you would be kind enough, in the fullness of time, to return it to me. I thought you would want to know that it is my intention to bequeath this memento to the Nation in order that future generations of Americans might fully appreciate what the founding fathers were trying to achieve, and not least the role you played. I look forward to hearing from you at some time in the future, and be assured of my sincere esteem and respect.

“I remain, your most obedient and humble servant, Thomas Jefferson.”

Simon placed an arm around his mother while his son completed the letter, which like his father and grandfather before him, he had learnt by heart.

“And will you promise me to teach your firstborn those same words and make sure he can also repeat them by his twelfth birthday?” Lord Hartley demanded.

“I give you my word,” said Robert.

Simon could not hold back the tears when he saw the smile of satisfaction on the old man’s face, although he feared he was seeing his father for the last time.

Extracted from An Eye for an Eye by Jeffrey Archer (HarperCollins, £22). Visit expressbookshop.com or call Express Bookshop on 020 3176 3832. Free UK P&P on orders over £25