Sarah Sands: An imperfect memory fends off a lifetime of shame

When I worked at The Daily Telegraph, our commercial fortunes were built on a fixed front-page advertisement for improving your memory. The firm that paid so highly for the slot knew that the elderly readership regarded memory as sacred, and its loss as a cruel separation from identity. What are we, if not a sum of our past? Yet for Jill Price, a 42-year-old school administrator and widow, memory is a sadistic jailer, imposing the past on the present, without sequence or respite.

Mrs Price suffers from a condition called hyperthymestic syndrome, which she describes as a split screen in her head, the past running alongside the present. J M Barrie may have described memory as roses in December, but to Mrs Price it is more like some hideous Leylandii.

She has forgotten nothing. She can recall every detail of every day of her adult life. There is no convenient editing of events. She says that she remembers "every bad decision, every insult and excruciating embarrassment".

It is a kind of morality tale about being careful what you wish for. Our memory fades for good reason. I doubt that searing grief – the loss of a child – could be softened or dimmed with time. But small horrors, social solecisms, clumsy gaffes, appalling drunkenness, can be quietly sent to the mind's trash bin. It is those sorts of flesh-wound memories that torment poor Mrs Price.

It may be conventional wisdom that we are the sum of our past, but do we have to be? What about a harmless bit of historical revisionism ? Or wiping out the past altogether? Boris Johnson, who in the run-up to the London mayoral election was described in The Guardian as an unelectable buffoon, now walks on water. His new communications chief, Guto Harri, says, without a hint of a smirk: "Boris has now proved himself to be a serious figure with great vision." Yet if this Colossus bestriding London were the unfortunate Mrs Price, he would have Liverpool on a loop in his head.

I was talking to an elderly Estonian lady last weekend about her 21st birthday party, which she remembered in photographic detail. I remarked that 21st birthdays seemed to have an eclipsing significance to women of her age. Indeed, I had interviewed an extremely old lady in France from the Bloomsbury set whose Audenesque features were transformed by the memory of her 21st.

By contrast she had very little to say about the past 40 years. My wise Estonian friend suggested sharply that there may have been nothing worth remembering.

I remember finding my schoolgirl diaries and wincing over the self centred, self-dramatising Emo-style ramblings. I could have summarised three years of misery memoirs with the summary: Nothing Much Happened.

Our inspiration at The Telegraph was Bill Deedes – soldier, editor, reporter. He had mischievously selective hearing at leader conferences. Any reference to his old age, for instance, went unheard. His excellent posthumous biography by Stephen Robinson had a profound and exhaustive clarity to it, including a chapter about Bill's feelings for a young female reporter. Dear Bill escaped the burden of memory only through his death.