Old Ale often refers to either a sweeter version of a Barley-Wine Style Ale or an aged version of what a brewery might call English Strong or Stock Ale. Burton Ale was Burton-upon-Trent’s signature beer before Pale ale and IPA. Originally, in the early 1800s, it was dark, made with brown malt–as pale malt was yet to be widely used–reasonably hopped, and fairly sweet with alcohol ranging from 7-12% abv. Brewers Michael Bass, Samuel Allsopp and William Worthington made good money shipping these beers to Russia and the Baltic but as the English Baltic trades fell apart in the early 1800s, and as trends at home went towards more hop-forward "pale ales" and "IPAs" made for the East India Company, Burton Ales became paler in color, drier in finish, and more heavily hopped, increasing to as much as 1-2 pounds per barrel of exclusively Fuggles and Goldings hops. As this new version of strong Burton Ale made it to London it was referred to as "Olde" or "Olde Burton":

Thus, we present to you "Old Burton Extra:" A large ale of considerable strength (8.9%abv), hopped with 1 pound per barrel Goldings in the kettle (77 IBUS) and another pound per barrel of Fuggles dry-hop, this ale drinks with huge citrus fruit esters, dark candied fruit, considerable dry bitterness, and faint notes of spicy hop, caramel, and fruitcake. But watch out because as the old 19th century song goes,

"Ne’er tell me of liquors from Spain or from France,
They may get in your heels and inspire you to dance.
But Ale of old Burton if mellow and right
Will get in your head and inspire you to fight."