What's the Deal with Jackon Lamb's Foot at the End of 'Slow Horses'?

I was going to post a screenshot of Jackson Lamb’s (Gary Oldman) foot in the final shot of the fifth season, but I think I’ll spare everyone that grisly image and just describe it: It’s gross. It looks necrotic, calloused over — like a foot that belongs to a zombie. We’ve seen a lot of Lamb’s toes over the years (the man doesn’t own a decent pair of socks), but never the entire foot.

But there was a reason for it. It was the payoff to a story Jackson Lamb told earlier this season that ultimately inspired his team to act. MI6 had Jackson and the rest of the team locked down in the Slough House offices, unable to help with the ongoing threat. That’s when Jackson relayed a story about another man being locked down in Berlin. The Stasi had “picked up a joe of mine and brought him in.” He explained how they used an aerosol can and a lighter to burn the skin off the soles of the man’s feet and made him stand for days (and drink his own urine).

I’ll spare the rest of the story (the “joe’s” pregnant girlfriend got worked over, too), except to say that it gave his team the idea to use a lighter and an aerosol can to free themselves from the MI6 agents holding them captive. It worked.

Afterward, Catherine Standish (Saskia Reeves) asked Jackson if the story was about him. “Don’t be daft,” he told her. “I made it up.” In that final reveal, however, it’s clear that he didn’t.

According to writer Will Smith, that last shot wasn’t originally in the script. “I’m pretty sure it was Gary’s wife, Giselle, who was later like, ‘Hey, what if we saw his foot at the end and he was scarred?’” Smith recalled. “Me and Gary were immediately like, ‘Oh my God, that’s amazing.’”

And so, the story Jackson said he made up became part of his traumatic backstory.

For what it’s worth, while it was a slow start to the fifth season, the slow burn was ultimately worth the satisfying conclusion.