If you see two X's in his lacing, the package is at the alternate drop site.
If he has 3 X patterns, you're burned! Make your way to the safehouse after losing any potential tails.
Glance quickly, agent, and keep moving.
> Every Tuesday, shortly after 7:00, a British MI6 officer would take a morning stroll at the Kutuzovsky Prospekt in Moscow. He would pass outside a designated bakery at exactly 7:24 a.m. local time. If he saw Gordievsky standing outside the bakery holding a grocery bag, it meant that the double agent was requesting to be exfiltrated as a matter of urgency. Gordievsky would then have to wait outside the bakery until a second MI6 officer appeared, carrying a bag from the Harrods luxury department store in London. The man would also be carrying a Mars bar (a popular British candy bar) and would bite into it while passing right in front of Gordievsky. That would be a message to him that his request to be exfiltrated had been received.
There's a great book that covers every single aspect of this escape, "The Spy and the Traitor" by Ben Macintyre. Rest assured that the British embassy had plenty of Mars bars and Harrods bags for this signal!
It reminds me a joke about Soviet spy arriving in Berlin and caughting stares from everyone around. What's wrong with my cover? Is something gives me out? Maybe it is a parachute? Or AK-47? Ah, it should be blue Slavic eyes! And he wears a sunglasses just in case.
I took it to mean that the MI6 agents were under diplomatic cover. It would not be strange for British diplomats to carry or eat British things, right? And it's also a decent defense against an accidental signal, since non-agents would naturally not have Mars bars nor bags from Harrods.
We met a celebrity once on a ferry. The only reason I even spotted her is because she was wearing a trench coat and ridiculous dark sunglasses like some sort of B movie operative. I happened to glance across the cabin just as she was walking past heading the same direction I was seated. Just a blink in full profile. After a moment of thinking, “no... she doesn’t live around here,” I turned to my wife and said, “was that?” And then looked at the woman across from us who had big eyes. When she passed outside the window it was definitely her. (Turns out her mother lived around there.)
Lady, you gotta work on your disguises. That outfit made you stick out like a sore thumb.
It's also only once a week that the timing is enforced, so they can vary things up throughout the week to hide that pattern in noise.
And the candy bar/Harrod's bag doesn't come into play unless Gordievsky needs an exfiltration. So it's not like they're noticing this weird thing where British diplomats always eat Mars bars every Tuesday. It would only happen once at most.
They know they're being surveilled. They can't change that. So they make their signal as mundane as possible.