We often take for granted treasures right on our doorstep. One of these Oxfordshire gems is Blenheim Palace, and this month’s castaway’ is a perfect guide to this World Heritage Site.

John Forster recently retired as head of the Blenheim Palace education service – but has not retired completely from the palace. He has taken on the role of archivist to the Duke of Marlborough.

I sensed that he is a teacher who loves storytelling and enthusing children. I was intruiged to know how he would he respond to the question: If you were shipwrecked on a desert island, which antique or work of art would you like to find washed up on the beach?’ John took me first to the Long Library and stopped in front of the Henry Willis pipe organ.

“There may be problems transporting this to my island,” he said. “It is the largest pipe organ in any private house in this country, perhaps in Europe.

“With four keyboards, a pedal board, 2,000 pipes and 52 stops, it is a superb example of the organ builders’ art, built by Henry Father’ Willis at the height of his powers in 1891. I admire and value it as a magnificent instrument, but it also holds personal memories.

“It needs to be played regularly and it has been my pleasure at Blenheim to do just that. Playing it on my island would give pleasurable memories of teaching the children who come to study the Victorian times in the Palace. We teach them to sing the old song Daisy Daisy bringing together Victorian themes of music hall, home entertainment and the bicycle age.

“A cheering memory on my lonely island would be to remember playing while groups of children around the organ swayed together as they sang about “the bicycle made for two”, often surprised but delighted to hear adult visitors joining in.

“I could remember many distinguished organists. Sir Arthur Sullivan played The Lost Chord’ at the inaugural concert. One recital, I shall never forget: I listened with 70 cathedral organists on a short break from a conference in Oxford. They chose a brilliant virtuoso, David Briggs, to perform for them. He did something very challenging on an instrument of this size and complexity; he extemporised, to the admiration of us all. I could not be bored playing it on the desert island, but another problem is likely to be powering it.

“Nowadays it runs on electricity but originally it was powered by water so there would need to be a hill with a water reservoir on the island. Maybe I should consider taking something smaller?

“Perhaps I should take something to remind me of one of the remarkable Blenheim personalities greatly admire. Sarah, first Duchess of Marlborough was a woman with the independence and spirit of woman living in the 21st century, who refused to be trapped by the limitations placed on her as a woman living in the 18th.

“A picture to take, which seems to me to capture Sarah’s forceful personality, is known as the “Mantilla Portrait”, painted by Charles Jervas after the death of her youngest son, Charles, in 1692.

“Without Sarah’s determination, it is unlikely the palace would have been completed. Sarah and John’s marriage was an attraction of opposites. He was a sophisticated courtier while she was fiery, tempestuous and capable of fiendish temper.

“On one occasion when they disagreed, Sarah became angrier and angrier but John calmer and calmer until in a fury of frustration she took her scissors and cut off her hair in front of him. He seemed not to react but after his death she discovered those same locks in a secret drawer in his desk. He gave no sign at the time but his love never failed.

“She was beautiful, capable – and very careful with money. Despite the restrictions on women, through her own acumen she became the richest woman in Britain, probably in Europe.

“She shrewdly ensured that the family wealth was protected from the unreliable next two generations so it was the fourth duke who had the necessary finance to commission Capability’ Brown to lay out the glorious landscape that created, arguably The finest view in England’.

“The Duchess’s forceful personality was also her downfall, ending her close friendship with Queen Anne who had granted Marlborough the Manor of Woodstock in which to build a house as a monument to his victory at the Battle of Blenheim.

“Wherever you stand looking at this portrait, Sarah’s withering gaze assesses the viewer. I am not sure that it would be a comfortable experience so I think my choice has to be something equally significant but possibly less judgemental.

My actual choice commemorates the Battle of Blenheim which, according to Winston Churchill, changed the political axis of the world’. The French were so thoroughly defeated that England was free to develop and extend its rule of the world’s trade routes which resulted in the largest Empire the modern world has known, the British Empire.

“So, I shall take to my island the magnificent, silver table centre piece of Marlborough on horseback after his victory writing his famous dispatch to his Duchess asking her to tell the Queen of his great victory.

“Made by the crown jeweller, Robert Garrard, it was commissioned by the Marquess of Londonderry on the engagement of his daughter, Frances, to the Marquess of Blandford, later seventh Duke of Marlborough. Garrards continued to serve the Royal Family, re-setting the crown for the Coronation in 1953.

“We wrote to the firm seeking more information on the centre-piece. They had deposited their archive safely away from Hitler’s bombs during the Second World War. Sadly the depository flooded and all the records were lost!

“Looking at the piece would remind me of the glory of the first Duke’s achievement 300 years ago, the reason for the building of the Palace. It will also remind me of Frances, the seventh Duchess, whom I have learned to admire.

“As a home during the time of the fifth and sixth Dukes the palace was an unhappy, lifeless place. But Frances and the seventh Duke had 11 children and made the palace a happy family home.

“Through her also, it will remind me of Winston Churchill, her grandson, who was born here but, neglected by his parents, was very much taken under her wing. To me it represents family life and love and above all I am a family man, so on the island it would remind me of my own family, too.

This piece is a superb work of art, greatly admired by the silver experts. The quality and complexity of its detail and texture is remarkable; the hide of the Duke’s horse in which every hair seems defined, the high polish of the horse’s hooves, the rich, mossy and seemingly soft bank beneath the horse, the intricate diamond work of the base and- should the island be inhabited I imagine the value of 50 kilos of silver could perhaps be realised and make my life secure.