It remains to be seen how this will make us safer

For the wider public, today's decision to investigate MI5's actions prior to the July 7 bombings raises the question of whether what might be found will make Britain any safer.

Ever since the attacks, victims' families and others have argued that the Government's failure to hold a fully independent inquiry has meant that a sufficiently rigorous analysis of whether they could have been prevented has never taken place.

That position has been backed today by Lady Justice Hallett.

As it stands, the evidence suggests that MI5's decision to focus on dozens of other terror suspects rather than the two, at the time unidentified, men who turned out to be 7/7 bombers Mohammad Sidique Khan and Shezhad Tanweer, was taken on the basis of what was known about each of them at the time.

Put simply, MI5 had to make a choice about who should be prioritised for surveillance. Even if that choice is shown by the inquest to have been wrong, it is hard to see how, when such difficult decisions emerge again, any conclusions that the coroner might make could ensure the right decision is taken.

In her ruling, Lady Justice Hallett concedes that some will ask "what is the point" of going over MI5's actions. Her answer, quite rightly, is that for "those who lost their loved ones there may be every point". For the rest of the public, the answer remains less clear.