91Èȱ¬

One of the big stories this week has been the verdict in the trial of four people found guilty of attempting to bomb the London transport network on 21st July.

While a trial is running, vast amounts of information comes out in open court. Much of it is not reported at the time because the news agenda moves on and we rarely report every day of a trial over many months. 91Èȱ¬ journalists also beaver away collecting more background and contextual information. Once the trial ends, and reporting restrictions are lifted, the whole story can be told - including some information which may not have been put before the jury.

One of the difficulties we face in telling the story is illustrating events which did not take place in front of cameras. Sometimes we use reconstructions - when actors show us how something might have been done. They're a useful device as long as they're clearly labelled - it is essential the viewer is not led to believe that they are seeing real events.

We did this on our report on the bomb plot (which you can watch for yourself here) - using information that was given in open court that the bomb was made from hydrogen peroxide and chapatti flour. A number of viewers contacted the 91Èȱ¬ to complain about this, one saying they felt it was "more or less a chemistry lesson on how to make a bomb". In our report, we made it clear that this was an exact science, and that the bomb failed because the chemicals were mixed in the wrong concentration. Indeed how the bombs were actually made, and whether they were viable, became a key issue in the trial.

We gave no details about the actual concentrations that were used - indeed, much more detailed information on bomb making is available on the internet. We used clearly labelled reconstruction pictures of a clear liquid being heated and flour being added - illustrating no more than had been said in court and widely reported in the press. We didn't include details of some of the other ingredients that are used to make this mixture into an explosive (again, this information is widely available). The pictures would be of no use to a would be bomb-maker.

Kate Robinson runs the team which made the background packages - she points out that a great deal of consideration went into what information was included.

"We obviously thought long and hard about what aspects of the bomb-making process we would show. All the information we used was already in the public domain and there are many facts which would be needed to make such a bomb that we did not go into - even though we know them. However, as the defence rested on their claim that this was a protest and not a workable bomb, we felt that it was important to show the public that these were truly viable devices. At all times we have taken into our decision making process the advice that was being given by the police at court. What we did would not enable people to make a device."

One final important consideration is that we need to give people enough information to know, in future, what might be suspicious. For example, had more people known about the use of hydrogen peroxide, then the police might have been warned about unusual purchases of large quantities in advance.