The beer below is brewed at Boon, but it's not a lambic (that's Frank in the background, incidentally):
It's a dark beer that's something akin to a dubbel, with a little borrowing from Edinburgh. The name goes back as far as Boon's mash tun--at least. You'll note that the name "Duivel" bears more than a passing resemblance to another gothic-scripted beer (Duvel). Indeed, they have the same infernal inspiration.
In the case of the older one, it goes back to the era when pilgrims visited Halle (near Lembeek) and its stunning cathedral which dates to the 13-15th century (it took a long time to complete). My memory of the exact details of the story fray here, but somehow this type of beer was brewed and named "the devil's beer"--I think because its heartiness and lusciousness distracted the faithful from the spirit and led them to cater to their flesh.
Boon recreated the beer from historical documents just to be brewed locally. Of course, the larger Moortgat, located on the other side of Brussels, took note. But nothing doing--when Boon referred to the historical record, Moortgat (whose own devil, Duvel, is spelled according to a local dialect) relented.
So now if you go to Halle, you have to specify either dark or light Du[i]vel or say Duvel Moortgat. Without a qualifier, you'll get the local product.