A beer of mixed fermentation for the first time brewed by Felix Van Roost in1869 of Brouwerij De Palmboom and named Jack-Op, in Werchter. In 1953 the brewery went into bankruptcy and was a year later taken over by Caulier from Brussels and later by the Brasserie de Ghlin. Brewing in Werchter continued till 1965 when the brewery was closed. The production of Jack-Op was transferred to Belle Vue, which was acquired by Inbev in 1991. Brewing by AB Inbev continued till 2008 when they stopped brewing the brand. But the beer did not vanish because since 2010 it is brewed - still under license and control of AB-Inbev - by Frank Boon. The addition of lambic matured in oak barrels deepens the taste of the beer and contributes to its long shelf life.