To some, images of dead soldiers are a vital historical resource. To others, they are an insult to fallen heroes. So when should we be allowed to film the bodies of those lost in past conflicts, asks documentary maker John Hayes Fisher.

The tightly-laced leather boots emerging from the Flanders mud are the giveaway that the body being carefully unearthed by archaeologists in front of me is that of an Allied soldier, killed in World War I.

This is Messines in Belgium and the New Zealand soldier, identified from his metal shoulder tags, almost certainly died while attacking the town early on 7 June 1917.

What I don't anticipate is the arrival of Belgian police who announce that if either my colleague or I photograph or film the body, we will be arrested, our camera equipment impounded and - possibly - the archaeological dig closed down.

Image caption John Hayes Fisher says he would be arrested in Belgium if he took this photo today

I have been following the archaeologists for three weeks for a television documentary about WWI. It's not the first time I've seen the remains of a dead soldier from that conflict.

Eleven years earlier and just a few miles from Messines, I filmed Belgian archaeologists as they recovered the remains of two British soldiers from WWI with a policeman in attendance. It was a moving experience for all involved.

What appears to have happened in the meantime is that the Commonwealth War Graves Commission (CWGC), the organisation that cares for war cemeteries and memorials around the world, has come to an agreement with the authorities in Flanders that human remains from WWI should neither be filmed nor photographed.

It just so happens that as the dead soldier from WWI is being exhumed at Messines, some miles east - on the battlefield of Waterloo - another British soldier's body has been discovered by different Belgian archaeologists. This time the body has been filmed and is all over the media.

I have been making history documentaries for more than 12 years and in that time have filmed the dead from all eras - Romans, Tudors, Saxons, Egyptians, as well as a 2,000-year-old Iron Age bog body whose flesh was so well preserved you could still see his fingerprints.

Image caption The preserved remains of the Iron Age bog body

In that time, only once do I remember anyone questioning whether it was right to film human remains. It now appears that, in Belgium, it's acceptable to film the dead from Waterloo but not from WWI.

So is there now some arbitrary cut-off point, the Crimean War (1853-6) perhaps? The Zulu War (1879), or the Boer War (1899-1902), after which time it becomes unacceptable to film human remains?

Belgium's role in World War I August 1914: Germany's invasion of neutral Belgium triggers Britain's declaration of war

Defending Ypres - to prevent Germany reaching the Channel ports - became a key Allied goal

Three battles were fought in three years over the town, leaving an estimated 900,000 dead

Mons has memorials marking where the first and last shots of the war were fired BBC History: World War I

Or should we simply never film or show the dead from any conflict?

The CWGC's policy on filming the remains of war casualties aims to preserve the dignity of men and women who have made the ultimate sacrifice.

"It should be remembered that the two world wars are not out of living memory and it is possible that the casualty may be identified," says spokesman Peter Francis.

A funeral for the fallen soldier "would be somewhat compromised if films and pictures of the remains of their relative had been publicly broadcast", he adds.

And yet all over the media, whether TV, magazines, books and in museums, images of the fallen from both World Wars are routinely shown.

I can clearly remember seeing graphic images of WWI dead in school books in the 1970s. Few can forget the haunting images of the emaciated bodies from the concentration camps of WWII.

Military historian Paul Reed, who has witnessed the exhumation of several WWI soldiers - including the Messines New Zealander - believes it's "important that we confront the realities of battlefield death as the beautiful soldiers' cemeteries sometimes belie this".

"The archaeology of the dead gives us a vivid insight into this without being ghoulish; and images of the dead should be part of our knowledge as much as wartime photographs of the battlefields," he adds.

Witnessing archaeologists working with WWI dead from both sides has given me a greater understanding of what happened on the battlefields of Flanders nearly 100 years ago.

And while I'm comfortable with that, I appreciate that for others it might be a little too soon to come face-to-face with the dead from the 1914-18 war.

John Hayes Fisher's WWI's Tunnels of Death - The Big Dig is on Channel 5 at 20:00 GMT on Thursday 8 and 15 November