Eighteen years ago, I walked over the road from the Birmingham Post and Mail’s old offices in Colmore Circus to attend one of the many press conferences I covered during my stint as a home affairs reporter.

The police briefings were usually held in a glassed, ground-floor room that could comfortably accommodate the local media, news agencies and the staffers for the nationals, who would roll up if a murder or multiple stabbing was sufficiently grisly.

On this occasion, back in April 1994, we were led up to large conference room inside the tower at Lloyd House, the headquarters of West Midlands Police. A big story in Birmingham might attract 20-30 journalists, including camera crews and radio hacks with their big, fluffy microphones. On this day, if my memory is correct, there were well over 100 reporters. This was a biggy and it remains the largest press conference I have attended.

We were there to hear the then chief constable, Sir Ron Hadfield, announce the findings of a three-year reinvestigation of the Birmingham pub bombings.

The new inquiry was triggered by the release of six men originally convicted of the mass killings but later cleared by the Court of Appeal.

The so-called Birmingham Six were innocent, so who was responsible for detonating the devices that killed 21 people and wounding 162 on November 21, 1974?

Sir Ron, publicly, did not have any satisfactory answers. The investigation cost £1.7 million, then a huge amount of money, but the 40 detectives assigned to the case had failed to uncover sufficient evidence to trigger criminal proceedings. That, at least, was the ruling of the Director of Public Prosecutions because the DPP had the ultimate say.

Had the police uncovered new suspects for what was then the UK’s worst mainland terrorist atrocity, only for the DPP to put the brakes on? We didn’t find out; we didn’t really find anything out.

In a bravura performance of political diplomacy, Sir Ron declared there were no more lines of inquiry and that his officers could not have done any more.

“The file, so far as we are concerned, is closed unless further evidence comes forward,” said Sir Ron.

The hunt for the IRA cell was abandoned. And we all trotted off to file our copy. I seem to recall the Post’s editors, to whom I reported, took the view there had been a whitewash. There was no other conclusion to draw.

But if that was the view then, in the days before increasing sophistication in forensic science, advances in DNA profiling and evidence collation, what view should we take today? The investigative landscape has changed dramatically since 1991, when the Hadfield inquiry into the bombings was launched. Is there nothing more to be said, and done, about the murder of 21 civilians?

I was only six when the bombings took place and I lived in a different part of the country. This may explain why I have so little recollection of the attack. I remember the later IRA killings of Lord Mountbatten and Conservative Shadow Northern Ireland Secretary Airey Neave and the slaughter of soldiers and their horses at Hyde Park and Regents Park.

My most vivid recollections of a mainland attack are of the Brighton bombing, which targeted Margaret Thatcher and killed five people.

In Northern Ireland, it is Omagh. The death toll in that blighted town, where 29 were murdered, comes closest to the loss of life in Birmingham.