I was on a shoot in the middle of Germany when I heard the news. My first reactions, I'm relieved to say, were the expected human ones: shock, disbelief, the well-worn litany. But before long a more calculating thought barged in: what does this mean for the series - a six-part history of photojournalism from the 1920s.
It had been sitting on the launchpad, ready to go since the beginning of the year and there had always been the nagging anxiety that, somehow, events might overtake us, particularly the last programme which dealt with the pressures facing photojournalists today. Chief among these, the film argued, was the whole Princess Diana phenomenon, which had undermined the well-established hierarchy of the profession by pushing classic subjects (wars, famine, atrocities, disasters) off the front pages of broadsheets and tabloids alike. As one of the photographers in our television series, a veteran of El Salvador and Tiananmen Square, put it: "You never know if the picture you risked your life to get is going to be replaced by another shot of Diana".
In the days following the crash, as the finger of blame swung from photographers to driver and back again, I remained in Germany, catching faint echoes of the cataclysm. But back in our office, snappers were hearing stories from their contacts in the profession which were hard to credit: photographers spat on and abused, verbally and physically.
One colleague was with photographers outside St James's Palace on the day of the funeral. He described the tense, beleaguered atmosphere in the pen: photographers in unaccustomed suit and tie, mobile phones turned off, conversations muted; then, as the cortege approached, the quiet was shattered by the loud, intrusive whirr and pop of the cameras as they went to work. No-one shouted "murderers" at them, but they all knew how people saw them that day. "We used to think the job was glamorous and exciting", one said. "Now we're as popular as traffic wardens".
Questions of ethics, of taste and decency, of the public's capacity for outrage versus its appetite for sensation, have accompanied the business of photojournalism from the outset. The American tabloids were the first to really appreciate that photographs rather than news sold newspapers. The tabloid sensation of 1928 was a photograph that no-one was supposed to see: a woman dying in an electric chair. Her name was Ruth Snyder and her trial, along with lover Judd Grey, was for the murder of her husband.
"Steal a picture, con a picture, do anything you could to get the picture. Pictures, pictures, pictures were on everybody's mind," says George Murray, a veteran of the era.
When guilty verdicts were delivered on Snyder and Grey, Harvey Deuells, editor of the New York Daily News, was prepared to "do anything" to get the picture he believed everyone wanted to see: Snyder dying on the electric chair. An elaborate plan was laid involving an out-of-town photographer, Tom Howard, and a specially made one-shot miniature camera, which was strapped to Howard's ankle. Howard attended the execution posing as a reporter (photographers were banned). At the critical moment, he hitched up his trouser leg, pressed the bulb in his pocket, and got the picture.
It appeared the following day under the headline: "DEAD!" The Daily News was widely condemned, and even more widely bought, putting on a million extra sales. In the words of a police reporter, Simon Michael Bessie, "It was vulgar, sensational and immensely popular".
The Snyder picture broke an important taboo in American tabloid journalism. After that, dead bodies became routine. A year later, shockingly graphic pictures of the St Valentine's Day Massacre, taken by Tony Berardi, were splashed across the front pages. Berardi was on the scene minutes after the murders took place, thanks to a tip-off from Al Capone himself. Confronted by the line of bullet-ridden bodies, his first thought was: "Where's the best angle to photograph this from?"
This hard-nosed attitude, which set the tone for photojournalism in this period, inevitably produced excesses. Charles Lindbergh was probably the first example of the celebrity-as-victim, hounded by the newspapers who believed they had created him. When his baby son was kidnapped and murdered, photographers ignored his pleas for privacy and restraint. One even broke into the mortuary and photographed the baby's dead body. That, however, proved to be a picture that even the hardest-boiled tabloid editor balked at.
Plus ca change maybe, but there is another aspect to the early days of photojournalism which today commands respect. In Europe in the late 1920s, Erich Salomon was pioneering an entirely new form of news photography. Impeccably dressed in white tie and tails, he gatecrashed embassies, conferences and summit meetings armed with the new lightweight Ermanox and Leica cameras, snatching pictures of world leaders in off-guard moments. The photographs earned him the label "the man with the candid camera".
According to Time photographer Diana Walker, a veteran of the White House press corps, Salomon still sets the standard for the work she does today. She adds: "All of these people who had appeared to the public as stuffed shirts, suddenly, there they are, smoking cigars, relaxing, their legs all over the place. This tells you something about these people, and it's illuminating and it's terribly important".
The series is full of examples of the admirable and the not so admirable aspects of photojournalism over the past 70 years. The justly celebrated work of Robert Capa, who on D-Day went in with the first wave of GIs on to Omaha Beach, appears alongside that of Sergeant-Photographer Len Chetwyn, a wily ex-Fleet Street photographer who steered clear of the front-line and persuaded soldiers to recreate their battles for the camera. Ron Galella, a paparazzo who specialised in celebrity stake-outs (and had his jaw broken by Marlon Brando), shares a film with Edward Quinn, a gentle, shy Irishman who, in the pre-paparazzi days of the 1950s, was able to win the friendship and trust of the stars who visited the Cannes Film Festival (including Marlon Brando, who was happy for Quinn to take his picture).
The final film, which will deal with the Diana story, will also include the story of French photographer Luc Delahaye, an intense, compassionate man, who, in 1994, stayed on in Rwanda after the world's media had decided the story was over. He witnessed and recorded the opening stages of the genocide that subsequently occurred. His pictures were the first visual proof that the terrible rumours were true. Delahaye is a million miles away from the popular image of the paparazzi, so universally reviled today. If the series achieves one thing, it will perhaps serve to remind us that in the history of photojournalism there is as much cause for pride as shame.
Tim Kirby is series producer of `Decisive Moments: The Photographs that Made History'. The series starts on Saturday 4 October at 8.10pm on BBC2