SAS: Who Dares Wins is nothing if not a gruelling test of physical and mental capacity, but tonight's episode stepped it up a notch.
Locksmith, member of band Rudimental, was told to "walk it off" after sustaining a knee injury when putting together a clipper - a small boat for two - on the beach.
Once they'd canoed their way across water, the recruits had to make a 30km hike, later with heavy kit.
Locksmith explained his motivation: "Being the east London Hackney boy that I am, getting me outdoors is a joke.
"I'm not an outdoorsy person at all. I went on one camping trip with my mum and I just moaned about it every day.
"At the same time I'm very competitive, and I want to win everything. I'll try my hardest to do that."
Later, he told: "I grew up on a street that was called 'Murder Mile'.
"It's taught me that you just have to take care of yourself, as best as you possibly can."
As he hiked, Ant Middleton and his special forces pals urged them on - with one even telling Locksmith to "walk off" his injury.
Locksmith pushed through, and made it to the end point where boxer Tony Bellew commended him for his efforts - and for always helping others.
Fans flocked to Twitter to express their astonishment and admiration.
One wrote: "@Locksmith bug respect head down & got to the end despite a f*****d up knee #SASWhoDaresWins."
Another gushed: "@Locksmith just watched SAS. Wow. Bro you are a legend and an inspiration."
A third joked: "'Just walk it off.' Sound medical advice for an injured knee lol."
A fourth tweeted: "'Walk it off, walk it off.' I think his knee is BROKEN, that SAS is SAVAGE."
