BJCP 16A
A very dark, sweet, full-bodied, slightly roasty ale that can suggest coffee-and-cream, or sweetened espresso.
Gravities are low in England, higher in exported and US products. Variations exist, with the level of residual sweetness, the intensity of the roast character, and the balance between the two being the variables most subject to interpretation. Some versions in England are very sweet (low attenuation) and also low in ABV (Tennent's Sweetheart Stout is 2%), but is an outlier compared to the other examples. These guidelines mostly describe the higher gravity, more balanced, export versions rather than the low alcohol, very sweet versions that many find quite difficult to drink.
Bristol Beer Factory Milk Stout, Left Hand Milk Stout, Lancaster Milk Stout, Mackeson's XXX Stout, Marston's Oyster Stout, Samuel Adams Cream Stout