They likened her to fire, him to water. She was the glamorous photographer, he was the writer with a conscience. Less than two weeks ago, Irene Vogt-Gotz and her husband Christian Gotz were among the most admired couples in the prosperous German city of Dusseldorf. She took pictures of the rich and powerful for the UN; he was the biographer of Bertha von Suttner, the German equivalent of Emmeline Pankhurst.

They likened her to fire, him to water. She was the glamorous photographer, he was the writer with a conscience. Less than two weeks ago, Irene Vogt-Gotz and her husband Christian Gotz were among the most admired couples in the prosperous German city of Dusseldorf. She took pictures of the rich and powerful for the UN; he was the biographer of Bertha von Suttner, the German equivalent of Emmeline Pankhurst.

Against all the odds, both had been diagnosed with cancer within months of one another and, to the relief of the many people who loved them, they had recently announced that they had both beaten it. But then came the celebrations, and with them the end of their seemingly charmed existence - because those celebrations began on board Concorde flight number AF4590 from Paris.

When the doomed Air France flight climbed above Charles de Gaulle airport last week, a 200ft plume of flames trailing from its port wing, the recovering Irene and Christian were on board. They had two minutes to reflect on their run of luck before it came down, disintegrating in a field outside Gonesse.

Of all the tragic stories that have come to light in the days since Concorde crashed, few have been more poignant than Irene and Christian's. They had been, by all accounts, blissfully married for the last seven years - it was her third marriage, his first. Irene, a vivacious, blonde 58-year-old, was well known in Dusseldorf as the owner of Foto Vogt, a photographic agency that, for more than 20 years, had been ubiquitous at the city's weddings, christenings and celebrations. It had become the "house photographer" for businesses ranging from Daimler Chrysler to Holiday Inn and Johnson & Johnson.

But it was as unpaid photographer to Ute Ohoven, a special ambassador for the United Nations Educational, Scientific and Cultural Organisation (Unesco), that Irene earned her name and the respect that went with helping a good cause. Ambassador Ohoven, the 54-year-old socialite daughter of Senator Manfred Ulmer, the Consul General of the Republic of Senegal, had earned a reputation as a fundraiser - she freely calls herself a "beggar" for children's causes. In 1994, she was made Unesco's special ambassador for children in need. Based in Dusseldorf, she became known in the German media as the "Queen of Charity", and she needed someone to record the whole thing.

"Irene offered to do it for nothing," says Anca Welscheid, Ambassador Ohoven's assistant, as we sit in her office, surrounded by Senagalese art and photographs taken by Irene. "Every time an important person came to visit, Irene would drop everything and accompany Mrs Ohoven to the airport or wherever she was needed.

"Many such meetings were about fundraising and publicity, so she always made sure she or one of her staff was there. She never charged anything, even though she had a business to run. When you picked up the phone to ask for her help, it was as if she only existed for Unesco, as if she was simply waiting there for you to call. She was a remarkable person."

Engagements followed - particularly at the Children in Need annual galas each October - with luminaries ranging from Yasser Arafat and the Dalai Lama to Chris de Burgh and Michael Schumacher. The event, with the help of Irene's pictures, consistently raised about $1m (£670,000) on just one night each year.

"She fitted in so easily, mixing effortlessly, but she wasn't like the people she photographed - it was a glamorous job, but she managed to remain modest," says Frau Welscheid. "She was simply nice and kind and caring."

Meanwhile, Christian had been busy making the transition from respected union representative to admired author. A handsome man with a shock of white hair, he had for years been on the board of Gewerkschaft Handel, Banken und Versicherungen, Germany's banking and insurance trade union, an extremely powerful organisation that huge influence over government policy. When he decided to call it a day, about a decade ago, trade unionists turned out in force to thank him. According to one, after he gave a speech they gave him a standing ovation and broke into a chorus of "Forever Young".

A successful career as an author followed, with four books published, most notably Die Rebellin Bertha von Suttner, a biography of the pre-First World War Nobel peace-prizewinning pacifist and suffragette. "He had a very well-defined sense of fairness and justice," says one of Irene's protégés, Susanne Weiland. She is now running Foto Vogt with two other young photographers, Tim Ahrens and Melanie Drechsler. But she says she is already missing the influence of Irene and Christian. "We always used to say they were like fire and water," she recalls. "Irene was always so passionate, energetic and ebullient, and Christian was always so considered and practical, correct and calming. It was a beautiful mixture. They were very happy together."

But, at the beginning of last year, disaster struck. A lump in one of Irene's breasts was tested and found to be malignant. Surgery followed and painful treatment was initiated on her lymph glands. "She had chemotherapy, which made her ill, and she lost her hair, but she never complained," says Susanne Weiland. "She just carried on working and, when she had to have her chemotherapy and take time off, she would come back and overwork to compensate. But she almost always managed to stay cheerful and positive. She wasn't going to let it beat her."

Last autumn, after reporting stomach problems to his doctor, Christian, then 59, was told that he, too, had cancer. The root of his problems was his oesophagus. "He had radiotherapy," recalls Weiland. "They used to support each other and I think that must have helped. Once or twice - but only very rarely - she would say, 'Why us?' Because they were worried that they would not have enough time together." Frau Welscheid adds: "I saw her with long hair, with no hair and in a wig, but I never once heard her complain. But at last year's gala, in October, she never turned up and sent her staff instead. Her operation and treatment had been so painful that she couldn't lift her camera."

The months of treatment passed - more for Irene than for Christian - until she was told early this year that her cancer cells had been eradicated. A few months later, spurred on by her success, Christian, too, was declared fit.

The change in their lives was palpable. They bought a new home in northern Germany, planning to scale down their work and spend more valuable time together. And they planned to devote much of this year to travelling. They had a couple of short trips to Sweden and Vienna, where Irene was born (Christian was from the north-west of Germany, on the border with the Netherlands). But the real holiday, the celebration that they had beaten cancer, would begin with a flight on Concorde on 25 July.

That would take them to New York and a rendezvous with the MS Deutschland, a five-star, luxury cruise liner. They would sail to Norfolk, Virginia, Port Canaveral in Florida for a visit to the Kennedy Space Centre, on through the Bahamas, Cuba and Mexico before journeying down the Panama Canal and on to Ecuador.

Of course, they never made it. "I was in my car when our trainee, Verena, called me and told me the news," sighs Susanne Weiland. "She told me to stop the car and then said Concorde had crashed and Frau Vogt was on board. I couldn't believe it - but then I couldn't believe she had booked it in the first place; she wasn't like that. She wasn't flashy - but I suppose it would be just like her to rush over the Atlantic. She was always rushing. We all got together at a colleague's house, and Renée, Frau Vogt's daughter, joined us. And we just waited for news. Eventually, the Foreign Office in Berlin confirmed she and Christian were on board. We were devastated."

Renée, who is aged about 40, is still too distressed to talk about the accident. She is understandably more concerned with taking care of Irene and Christian's grandson, four-year-old Florian. "He is old enough to know his grandmother has gone, but he isn't old enough to cry about it yet," says Weiland. "He says things like, 'Grandma has gone to heaven', but there are no tears. Perhaps at the funeral." As yet, no one knows when that funeral will be. This week, the French authorities were able to identify Christian's remains, but on Wednesday it was still thought they had not identified Irene's.

In the offices of Foto Vogt, activity seems sluggish and silent. Susanne Weiland and the others are determined to keep the business going, in memory of Irene, but there is a strange sense of absence hanging in the air. "We haven't had a chance to miss her yet," says Weiland. "She was only due back on 10 August, so it feels as if she is still on holiday. We're quiet at the moment. I'm sure when we get busy, when I need her the most, I'll miss her very much."

In the Grafenberger Allee offices of Unesco beneath the wallhanging presented by Queen Wangchuk of Bhutan (whom Irene photographed), there is a heavy sense of loss too. "She was a wonderful woman - completely selfless - and she did so much for us," remembers Ambassador Ohoven. Then her assistant Frau Welscheid says something that, on first hearing, sounds odd. "One of my colleagues took the news of the crash over the phone and at first I thought it was someone calling to say one of them had died of cancer. When he told me it was an air crash, and they were both dead, I felt relieved. It would have been awful for one of them to have been left behind."

And you can't help thinking that perhaps she is right.