From 1911:

One pint of thick cream, or rich milk (if it should be a little acid stir in enough sugar to sweeten it). Mix with the cream a quarter pound white sifted sugar. Let it stand half an hour, then add three wine glasses of sherry or Madeira wine (or brandy). Whip to a stiff froth and fill the glasses. Either churn the cream, using a small syllabub churn, or pour the cream out upon a small flat dish and whip with a silver fork or egg beater.