THERE are no words. Oh, but there are. Words that can distil something of the essence of the boy - or was he already a man? I can only try to convey the pain of the hurt, the pride of the parent, the disbelief over repeated tragedy - the loss of a daughter and now, a son. But my wife Rosamund and I do believe, as Plato first declared, that there is a Heaven beyond our consciousness, and that Charlotte and Julian are together in some immortal form - a pretty wonderful combination.

'You must remember children are a gift from God, they are only lent to us': Nigel and Ros Starmer-Smith and their son Charles mourn the death of Julian

There is a terrace on the third floor of the John Radcliffe Hospital, Oxford. I must have spent quite a few hours there during the last weeks of Julian's illness, sometimes with Ros, sometimes with a friend, sometimes alone. Hour by hour, night by day, my wife and our other son, Charles, maintained a mask of hopefulness by Julian's bedside.

On the terrace, I - the weakest of the three of us - could slip off that mask for brief moments. From the terrace there's a striking vista across the leafy Thames Valley, a few Oxford spires upstanding, enclosed by the hills of Cumnor Hinksey and Beckley. In the midst, so clear at sunrise, stands the tower of St Nicholas' Church, Old Marston, close by the home of my 92-year-old father.

In this landscape are locked all my childhood years, school, university, and lots of family happiness. In those desolate hours and days, as I stood and stared out, so many memories returned to me, while I tried to pierce the mental numbness, searching my soul to make some sense of the senseless. My 19-year-old treasured son lay close by, two floors above, fighting to stay alive as T-cell lymphoma, a rare form of cancer, ravaged his young body.

Julian - Jules, as he preferred it - so full of life, athleticism and fun. Surely life could not desert him? It had all been so sudden.

Late last August Julian had returned from a mission to south-west India, where he and several school friends had spent weeks barrowing concrete and carting bricks to build a simple house for a local family. A week later he was in the Infectious Diseases Unit at the Churchill hospital, Oxford, with a high fever. Whatever it was left him as quickly as it came. All was well and life returned to normal.

We can only reflect now on whether this brief illness might have been the catalyst for something more serious. Seven months later, newly qualified as an advanced skiing instructor after the second epic trip of his gap year to the snow caps of Quebec, Julian's high fever returned. He flew into Heathrow; within 48 hours he had been re-admitted to hospital with soaring temperatures and intolerable sweats sapping the energy of his fit young body.

The painstaking search by specialists to identify the cause began. As each analysis of blood, liver and bone-marrow tissue eliminated possible diseases, our fears grew. Finally the lymph node biopsy revealed that cancer was invading his blood. He was transferred to John Radcliffe and it was there, on Good Friday, that Ros and I were gently told the worst possible news. That this was a variant of T-cell lymphoma; that his chances of survival were slim. Rightly, Julian was told, too, but not that he had little chance of recovery.

Nine-and-a-half years ago, Julian's sister Charlotte died on Remembrance Day, aged 16, of haemophagocytic anaemia, another rare disease. Charlotte's illness had exhibited similar characteristics, but there was no diagnostic connection. In her case glandular fever had been the trigger of a rare type of blood disorder which, like Julian's, was to take her from unbounded vitality to death in just five weeks.

Charlotte's death left Ros, Charlie, Julian and me broken-hearted and bemused. For almost 10 years, scarcely a day has passed without some memory of her infectious laughter, her sparkling eyes and carefree style. What joy she brought us; what a loss to bear. I could not stop thinking of Charlotte as I paced the hospital terrace, Julian's condition becoming ever more desperate, the consultants more troubled and rightly short on reassurance. But no, this could not be happening again; it had to come right. Such a tragedy could never be repeated in one family. Please God, please, spare my wonderful child. But there was to be no answer, no consolation, no prayed-for miracle.

Throughout this agonising time there was Ros, ministering with such courage and love to her son, coping so gently with the horrific side-effects of two weeks of chemotherapy. Her words to me on Charlotte's death came to mind; words first conveyed to her by the Great Ormond Street chaplain when, as a staff nurse, she had been deeply hurt by the loss of a particular child patient. "You must remember, children are a gift from God, they are only lent to us." So, once again, was our brief tenure of loan about to expire?

It would be easy to say that the second time round we were better prepared, and to an extent we were. We could anticipate the physical and psychological agonies we would be forced to confront. But in truth, we never allowed ourselves to believe that history was repeating itself. And then there was Charles. As the days and nights passed and merged into one, Ros and I worried desperately for our other son, now 22, a young man who had lost his adored elder sister, and had now to look on as the life, but not the spirit, of his brother ebbed slowly away.

Charles was everything to Julian; his role model, his confidant, his best friend. And Charles reciprocated in kind. Julian's hair had been lost through chemotherapy; Charles shaved his head, too, in an unspoken pact of fraternal loyalty.

Even when Julian's voice had left him, he would mouth, "I want Charlie". And Charles he had, hour by hour, at his bedside, holding, caressing, gently talking. Each of us, on our own with Julian at a different time in those last few days, received a truly powerful hug from a frail, once so athletic boy, and those whispered words, "I love you".

Supporting our small family group was a medical team beyond reproach. Dr Chris Hatton, his fellow consultants, registrars and doctors did everything possible in their fight to save Julian, as far-flung consultations and transatlantic advice was to no avail. Throughout, the nursing team on Ward 5E gave Julian every loving care.

We never allowed ourselves to consider that within days we would be burying Julian alongside Charlotte in the country churchyard at Rotherfield Peppard. To do otherwise would have been a threat to our sanity. We let our instincts for self-preservation take over; we clung on to hope, however remote, to the very end.

Now we can only see with our eyes shut, that affectionate, athletic young man who has touched the lives of so many. For his mum and me, there's the lad at Radley College, his unembarrassed hug and kiss when we came to pick him up for Sunday lunch.

There were myriad phonecalls - whether he was at school or away on his travels - his first enquiry of us always, "Are you all right?" So it had been ever since Charlotte died.

Home and abroad we see him, generous to a fault, at the hub of the social scene, blond highlights in his hair, dyed latterly to a shock of ice blue. He's there, too, at BBC 5 Live, working as he did to save money for his travels, telephonist, office-boy, friend to all.

There's the proud car owner. How he loved his car, he funded it himself; all the latest gadgets, and the inevitable go-faster stripes. And this time we're on the touchline at Radley College, or Henley RFC, watching the scrum-half with the most devastating break off the back of the scrum I ever saw, the smallest, but fastest, player on the field. A modest smile, as always, but never a boast.

As with Charlotte, it's no use to dwell on what might have been. For Ros and me there are positive things we can cling to, not just the memories. We've gained an understanding, through all our children, of the depth and quality of friendship, intimacy and mutual support that exists between so many boys and girls of today, as the awkwardness and formality of a generation ago has been swept by the board.

The offer of Radley College to stage his funeral last Thursday was a generous and loving testimony. A thousand people were in the college chapel, where Julian was carried to his rest and read to by some of his closest friends, giving comfort to us all, and making us, his parents, proud for ever.

When Charlotte died, we established a charity fund which raised nearly half a million pounds. The Isolation Unit at the Royal Berkshire Hospital, Reading, stands in her name. This time donations will go towards the establishment of Research Fellowships at Oxford University in Julian's name. These will be set up under the guidance of Dr Chris Hatton, head of the medical team which fought so hard to save our son. It will help, we hope, to unearth the causes and, God willing, a cure for this particularly aggressive form of cancer which, though still rare, is increasing in young men at an alarming rate.

In the final analysis, it seems we have a choice. As Dylan Thomas put it, we could, "Rage, rage against the dying of the light", or, as we prefer, follow the words of a close friend of Charles who sent this poem to him the other day: You can remember him and only that he is gone, Or you can cherish his memory and let it live on, You can cry and close your mind, Be empty and turn your back, You can do what he'd want, smile, open your eyes, love and go on. You see, then, why there is in fact no choice. For Jules' sake, buoyed up by his radiant smile and his exemplary care for others, we turn our face to the wind.

For me, for Ros and Charlie, these are the only words we need.

• Contributions to The Julian Starmer-Smith T-Cell Lymphoma Fund should be sent c/o Dr Chris Hatton, John Radcliffe Hospital, Headington, Oxford OX3 9DU.