Source: Darryl Richman (firstname.lastname@example.org), HBD Issue #1570, 11/4/94
But even lower gravity beers than the 1.035-1.040 bitters come from the industrial revolution and the large coal mining industry that was needed to feed it in the last century. These beers, called Mild Ale, usually have gravities in the low 30s, and even down into the high 20s. (There are a few examples of milds into the 1.045 range, but they are the exception that proves the rule.)
What really distinguishes Mild from bitter is that Mild has low hop bitterness. Mild is usually darker than bitter, but there can be substantial overlap in the amber range. Some Milds have distinctive hop character in the nose and flavor, but usually the bitterness they have -- when they have it -- is derived from roasted malt. This can give Milds a nutty character, which can be pleasing with a distinctive and fruity yeast. Brains' Dark (1.035 OG) from Cardiff is a fine example of this type of Mild.
Sparge with 8 gal. untreated soft water. Boil off 3.75 gal. during two hours, adding ~24 IBUs of Kent Goldings hops (based on the final volume of the beer, in this case it was 170 gm of 6% alpha acid pellets).
The yeast starter was stepped up twice, with a quart and then a half gallon of wort starter. The primary finished in 4 days at 60F, and I racked into carboys for a week of clarification before kegging.
The FG was 1.010, for a batch of beer that was about 3.2% by volume, or about 2/3rds the strength of a standard beer. It was a dark brown in color, with a sweet initial palate and a (relatively) full body and a dryish finish. The yeast character showed through in the middle, although there wasn't a lot of fruitiness, probably due to the low fermentation temperatures.