The former Mad Men star took time out from filming on Good Omens to drop in at Buck’s Bar.
The bar’s Instagram page shared a selfie of Hamm posing with one of the staff.
They posted: “What a star studded day in Bucks today! 🤯
“We had Jon Hamm pop in for a quick bite to eat and our very own Connor managed to nab a quick selfie 📸 Hope you enjoyed your meal, Jon!”
Hamm stars in the Amazon hit as the Archangel Gabriel - and was recently spotted in Edinburgh with co-star Michael Sheen.