A few Saturdays ago, I took a long walk around a field in North Dorset.

Not just any field (although I suppose you could say it is just any field now).

I drove up there on a particular day.

Seventy four years ago that morning, the area was alive with aircraft and gliders at the start of one of the most written about operations of World War Two.

Operation Market Garden was a daring throw of the dice aimed at flying thousands of Allied airborne troops hundreds of miles behind enemy lines to capture the bridges across the Rhine in Occupied Holland and then storm into the Ruhr, Germany’s industrial heart.

The aim was to bring the war to a swifter conclusion.

All did not go to plan, not least at the bridge that became synonymous with the episode, Arnhem.

In any event, the airfield at Tarrant Rushton played a part in delivering the airborne forces to their destination.

A small memorial is sited at the entrance.

Every year brings one anniversary or another of one conflict or another. Next year will be the 75th anniversary of D Day for example.

In two weeks, we mark 100 years since the end of World War One. The past four years remembering and commemorating 1914-1918 has been an emotional time, even though there are now no veterans left to tell their stories first hand.

Before long it will be the same with the 1939-1945 conflict.

But in both cases (and of course many others) we have the testimony left behind, both written and broadcast, documents and archives and the work of historians, who we can usually rely on. We cannot always take that for granted though.

I spent all day Wednesday and Thursday reading one of the most powerful and emotive books I have ever come across and it left me wondering how it was that I only picked it up some 13 years after it was published and after two visits to Auschwitz myself.

Denial by Deborah Lipstadt (subtitled Holocaust History on Trial) tells the story of the notorious libel case brought against her by David Irving, biographer of Hitler, Goebbels and a prolific writer of numerous books on the Third Reich.

In her 1993 book ‘Denying the Holocaust’, Professor Lipstadt called Irving “one of the most dangerous spokespersons for Holocaust denial.”

He sued and a gripping defamation case was heard at the Royal Courts of Justice over three months in 2000.

It with Irving’s account of history (including that the gas chambers at Auschwitz never existed and that there was never any organised, systematic operation to annihilate the Jews) was demolished.

His work was described by the Judge as “perverse, a travesty, misleading and unreal.”

The demolition of Irving, a racist and an anti-semite the court unequivocally heard, set back the cause of Holocaust denial years and it has never recovered.

Looking back at the trial now all these years later, it seems astonishing that his grotesque historical distortions could ever have been taken as the truth by any right-minded human being.

Yet Irving wrapped up his lies and manipulations around his one-time reputation as a serious historian.

That another Irving could emerge is not impossible, particularly as we get further and further away from the events.

Another reason that everyone who cares should play a part in keeping alive the memories, the sacrifices and the truth of what happened.

One of the most chilling, but also most heartbreaking things I ever read was Primo Levi’s account of his time in Auschwitz.

Feeling he was dying of thirst he reached out to break off an icicle. A guard snatched it away from him.

Levi asked him: “Warum?”

The guard replied: “Hier is kein warum.” Here there is no why.