My guess is they used heavily toasted oak chips/spirals.
Oaking is something that, in a beer, for my palate, it has to age quite a bit before it doesn't have an oaky bite to it.
the few smoked beers I had I didn't care for, but they didn't remind me of oak either, but I've never had a toasted/burnt oak beer
Primary: English Mild
On tap: Pale Ale, Lancelot's Wheat, English Brown Ale, Steam Beer, HoovNuts IPA
Bottled: MOAM, Braggot, Raspberry Melomel, Merlot, Apfelwein, Pyment, Sweet mead, Cabernet
Gal in 2009: 27, Gal in 2010: 34, Gal in 2011: 13, Gal in 2012: 10