August 1914: British soldiers, newly arrived in France prepare to go to the linesGetty/Three Lions

One million heroes of the First World War have been "forgotten" by their descendants, a new geneological study has revealed.

Family history website Ancestry.co.uk has shown that three in 10 modern-day relatives of World War One veterans are unaware of their military heritage, and many lose the opportunity to find out about their link to the Great War when family members pass away.

For the study, researchers mapped population growth among veterans of the Great War to quantify how many Brits today have a WWI ancestor.

After comparing the 26.7 million figure with the number of people actually aware of such heroes in their family's past, the results showed a significant "ancestral knowledge gap", with 7.5 million Britons in the dark about their family connection to the Great War.

According to the report, this equates to 1.26m soldiers forgotten by their descendants, but the research also suggests why such important family knowledge has been lost.

Most of those unaware of having WW1 ancestors assume that they would have been told about them, when in fact many veterans never spoke to their children about their role in the conflict - wanting to put the trauma they experienced in the trenches behind them.

In addition to those completely in the dark, many Brits have heard a rumour of a connection to WWI but are unaware of the details, with most of these people reporting that their grandparents died before they could ask them about the details of their WWI war hero ancestor.

Yet those who know about the WW1 ancestry say they clearly see the benefit of such knowledge. According to Ancestry.co.uk, half said they were more grateful for what they have today, with a similar number stating they felt humbled when they think about the bravery of their ancestors.

To help people discover and learn more about their veteran ancestors, Ancestry.co.uk is making its WWI Medal Index Cards available and completely free to use at Ancestry.co.uk/world-war-1. An additional 10 million records will also go online to celebrate the WWI centenary.

Senior content manager of Ancestry.co.uk, Miriam Silverman, said: "Many veterans never spoke about their experiences in the Great War upon returning home, so it's understandable how so much knowledge could have been lost, especially if people missed the opportunity to speak to their older relatives before they died. The result is a widespread and tragic lack of personal knowledge of our WWI ancestry.

"We believe all those who served in WWI deserve remembering and want to help bridge this knowledge gap. That's why we've made all of our WWI medal records universally available and completely free to use. We hope that this will allow millions of Britons to reconnect with their past and feel the pride that so many of us have for our war hero ancestors," she added.