Was Buçaco a British or French victory?

Was the Battle of Buçaco a British victory or a French victory?

An Anglo-Portuguese victory: Wellington inflicted heavier losses and gained the time his strategy required, even though the French continued their advance.

Wellington was already conducting a planned withdrawal toward the Lines of Torres Vedras. At Buçaco, his smaller Anglo-Portuguese force is credited with inflicting two to three times the casualties it suffered. The battle also bought time for those defenses to be completed, which was the immediate strategic purpose. The French could claim that they continued to push the defenders back, but withdrawal was part of Wellington's plan. On that assessment, Buçaco was an Anglo-Portuguese victory despite the continued French advance.