A British Brown Ale is fairly versatile, and can be paired with a broad range of ingredients. It’s a subtle beer that allows some ingredients to blend in, and find the right balance between the base style and the addition.
The highest rated additions tend to be more savory than sweet or sour. Nuts like peanut butter, hazelnut, and pecan match the potential nuttiness of the style. (Read my brew log of a Pecan British Brown Ale.) Liquor additions like bourbon and whiskey are also good additions, although whiskey would be a better match geographically.
A British Brown Ale also would provide a solid backbone for some spices. Chai, cinnamon, and seeds of paradise would make good additions, and while it’s lower rated, chamomile could be used as well.
Most of the additions that wouldn’t work well lean toward sour, but a notable exception is the current leader- cherries. I think a British Brown Ale would make for a good base, but perhaps not for sour cherries.
BJCP Style: 13B