Pour into a saucepan three pints of mild ale, one table-spoonful of sifted sugar, a blade of mace, a clove, and a small piece of butter; and bring the liquor to the boil. Beat up in a basin the white of one egg and the yolks of two, mixed with about a wine-glassful of cold ale. Mix all together in the saucepan, then pour into a jug, and thence into another jug, from a height, for some minutes, to froth the flip thoroughly but do not let it get cold."
"Cakes and Ale" by Edward Spencer, 1913, page 216.
I like the author's warning at the end of this recipe:
One quart of mild ale in a bowl, add one wine-glassful of brown sherry, the same quantity of old brandy, a table-spoonful of sifted sugar, the peel and juice of one lemon, a grate of nutmeg, and an iceberg.
N.B.- Do not insert old ale, by mistake. And for my own part, I think it a mistake to mix John Barleycorn with wine (except champagne) and spirits."
"Cakes and Ale" by Edward Spencer, 1913, page 214.
Though you'll notice that he happily mixes beer, sherry and brandy in this recipe:
Squeeze the juice of a lemon into a round of hot toast; lay on it a thin piece of rind, a tablespoonful of pounded sugar, a little grated nutmeg, and a sprig of balm. Pour over these one glass of brandy, two glasses of sherry, and three pints of mild ale. Do not allow the balm to remain in the misture many minutes."
"Cakes and Ale" by Edward Spencer, 1913, page 226.
Let me know if you give any of these recipes a try. I suspect getting hold of the Mild Ale will be the trickiest part.