The Jurassic Park star's relative, Lieutenant Colonel Bob Ingham, fought with the Australian and New Zealand Army Corps (ANZAC) in the First World War and died in Belgium in the summer of 1917.

He was buried in the Lijssenthoek Cemetery near the town of Ypres, and Neill made the journey to his grave for the first time as part of filming for a new documentary called Why Anzac.

Neill tells viewers, "This is an emotional moment for me. I've never been here before. I'm finding this pretty distressing."

The actor then broke down in tears as he read the inscription on the headstone which had been requested by his grandmother: "So he passed over and all the trumpets sounded for him on the other side."

Neill adds, "We knew we wanted to see Bob's grave but I had no idea how it would affect me. I was a bit blindsided by that. It really surprised me. A couple of years ago my son worked out where Bob was buried and went and visited the grave and I'd always wanted to go and see it. But it was those words at the bottom that really got me. They were my grandmother's words. They were her request and her view about what had happened to Bob."

Why Anzac airs in Australia on 21 April (15) ahead of the Anzac Day of remembrance on Saturday (25Apr15).