BBC viewers were left very emotional on Thursday as they learned of Vicky McClure's tragic family history during the latest episode of Who Do You Think You Are?

The Line of Duty star, 41, retraced her relative's past on the genealogy show where she learned the heartbreaking fate of her great-grandfather, who was a Japanese prisoner of war in Taiwan, during World War II

In one particularly poignant scene, Vicky broke down in tears after discovering how her maternal great-grandfather Harry Millership had died and the 'horrific' hardships he'd endured before his death.

And it wasn't just Vicky who was emotional as tearful viewers soon took to X, formerly known as Twitter, to express their feelings over the episode, with one remarking it was one of the 'saddest ever'. 

Viewers shared: 'Tears shed for the poor prisoners of war held in Japanese camps in WWII - an emotional watch.'

BBC viewers were left very emotional on Thursday as they learned of Vicky McClure's tragic family history during the latest episode of Who Do You Think You Are?

BBC viewers were left very emotional on Thursday as they learned of Vicky McClure's tragic family history during the latest episode of Who Do You Think You Are? 

In one particularly poignant scene, Vicky broke down in tears after discovering how her maternal great-grandfather Harry Millership had died and the 'horrific' hardships he'd endured before his death

In one particularly poignant scene, Vicky broke down in tears after discovering how her maternal great-grandfather Harry Millership had died and the 'horrific' hardships he'd endured before his death

'One of the saddest episodes I’ve ever watched but how proud is Vicky McClure of her Great Grandad. RIP Harry Millership.'

'Vicky_McClure that was incredibly sad. God bless Harry'; 'That's it I'm gone [crying emoji]'

'Blown away by Vicky McClure’s family story #whodoyouthinkyouare. Poor Harry to have escaped the darkness of the Yorkshire coalfield, only to die in a mine thousands of miles from home

'@Vicky_McClure what a moving emotional experience for you. He really would have been proud of you and your quest. I did something similar a few years ago in N France and it will stay with me for ever.'

During the episode, she discovered the awful reality of the journey from Singapore - where Harry's regiment had been posted in 1941 - to the Taiwanese POW camp where he was interned after the Japanese attacked on December 8. 

Vicky learned that Harry would have been taken in an airless hold with very little in the way of supplies and, upon arrival at the POW camp, forced to work in a copper mine. 

Harry sadly died at the camp after falling 30ft to his death, with the actress taking comfort knowing he died instantly. 

Reflecting on her job in the spotlight, Vicky explained that she has 'a very vivid imagination', adding that she's 'battling with it' while exploring Harry's struggle 6,000 miles from home. 

The Line of Duty star, 41, retraced her relative's past on the genealogy show where she learned the heartbreaking fate of her great-grandfather, (second right) who was a Japanese prisoner of war in Taiwan , during World War II

The Line of Duty star, 41, retraced her relative's past on the genealogy show where she learned the heartbreaking fate of her great-grandfather, (second right) who was a Japanese prisoner of war in Taiwan , during World War II 

During the episode, she discovered the awful reality of the journey from Singapore - where Harry's regiment had been posted in 1941 - to the Taiwanese POW camp where he was interned after the Japanese attacked on December 8

During the episode, she discovered the awful reality of the journey from Singapore - where Harry's regiment had been posted in 1941 - to the Taiwanese POW camp where he was interned after the Japanese attacked on December 8

Harry sadly died at the camp after falling 30ft to his death, with the actress taking comfort knowing he died instantly

Harry sadly died at the camp after falling 30ft to his death, with the actress taking comfort knowing he died instantly

'My head's all over the shop and I'm learning information that is just horrific, and it's my great grandad, it's my mum's grandad - it's too close,' she said

'My head's all over the shop and I'm learning information that is just horrific, and it's my great grandad, it's my mum's grandad - it's too close,' she said

It wasn't just Vicky who was emotional as tearful viewers soon took to X, formerly known as Twitter, to express their feelings over the episode, with one remarking it was one of the 'saddest ever'

It wasn't just Vicky who was emotional as tearful viewers soon took to X, formerly known as Twitter, to express their feelings over the episode, with one remarking it was one of the 'saddest ever'

'My head's all over the shop and I'm learning information that is just horrific, and it's my great grandad, it's my mum's grandad - it's too close,' she said.

She went on: 'I want my family here with me. I feel really alone in this because it’s so much to take in, yet I feel terrible for feeling like that because he was alone and didn’t make it home. 

'I feel connected, which is weird because I never even met him.'

Vicky also admitted she was nothing like her 'hard as nails' TV characters while tracing her ancestors and travelling to a prisoner of war camp in Taiwan.

She said: 'There's been a lot of it I've not found easy. For all the action-packed shows that I do and the fact that I might seem hard as nails in certain things, I probably couldn't be further from that'.

Elsewhere, to commemorate the 80th anniversary of the D-Day landings earlier this year, the BAFTA Award-winning actor spoke about another family member who served in WWII for an ITV documentary.

Vicky's grandfather Ralph McLure, 97, explained how he narrowly escaped death when his landing craft was hit by enemy fire during the invasion of Normandy.

Elsewhere, to commemorate the 80th anniversary of the D-Day landings earlier this year, the BAFTA Award-winning actor spoke about another family member who served in WWII for an ITV documentary

Elsewhere, to commemorate the 80th anniversary of the D-Day landings earlier this year, the BAFTA Award-winning actor spoke about another family member who served in WWII for an ITV documentary 

He was just 17 when he signed up to serve in the Royal Navy and was deployed as a signaller on a landing raft tank on that historic day.

Sharing the respect she felt for her grandfather and reflecting on the importance of remembering D-Day, Vicky said: 'It is so important to keep this history really close and make sure the kids know about it.

'It's so important that people like my grandad are able to recall it and I'm sure there are many veterans who felt unable or didn't want to do that.

'So any kind of information we can have that comes in about that history is important.'