The special – which marks the RNLI’s bicentenary – celebrates the organisation’s efforts to save lives in some of the most perilous conditions it ever faced. Despite near-impossible circumstances, the RNLI saved no less than 6,376 people.

Volunteer crews were there for the evacuation of Dunkirk and the Battle of Britain. In the Saving Lives at Sea special, O’Leary talks to family members of crew members and local historians. Combined with archive footage, the show tells the stories of an extraordinary group of people.

“What I find so brilliantly unique about this story, and why I’m so proud to be involved in it, is because for this five- or six-year period where the world is trying to kill each other, you have this kind of raggle-taggle group of largely older men whose specific role is to save lives,” said O’Leary. “That's pretty much all they care about.”

“It's so intertwined with what the RNLI stands for and their mantra. They don’t care where you’re from. They don’t care what colour your skin is. They don’t care if we’re at war with you. If you’re a soul in the sea, all they want to do is get you out.”

The special airs on BBC Two at 9.00pm on Tuesday 12 March.