Ironbark

Screenwriter Tom O'Connor found out as much as he could about Greville Wynne and Oleg Penkovsky. Their relationship is mentioned in several books but only in fragments. "There's enough to understand the basics," O'Connor stated. "A lot of the events were and remain classified, and so sometimes, finding out what exactly happened was a challenge because there is active misinformation being put out by both sides. People don't necessarily want everything on-the-record."

In a panoramic shot of Moscow, Wynne walks along the embankment opposite the building of the Ministry of Defense. Although it was built in 1951, a late 2014 annex with two-headed eagles on the friezes is visible. In Soviet times, two-headed eagles were a symbol of czarism and under no circumstances could they appear on an official building in the center of Moscow.

Vintage news footage of the real Greville Wynne is shown before the end credits.

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