Criminal past of Samantha Womack's great-grandfather
15 August 2012 Last updated at 03:02 BST
While researching the military career of her great-grandfather, Alexander Cunningham Ryan, former EastEnders actress Samantha Womack discovered a shocking fact about his past.
Ryan deserted his post at the Royal Garrison Artillery in Plymouth and was not on duty when he was expected to be.
Colonel Edward Dawes also informed Womack that her great-grandfather had been charged with a criminal offence and sent to prison.
Who Do You Think You Are is on Wednesday BBC One,15 August at 21:00 BST.