I'm suprised I didn't post about this back in the day ... or I did and didn't tag it meaningfully ;)
I managed to track down a copy of
Margaretta Acworth's Georgian Cookery Book. It was published in the 1980s and the Prochaska's (who are the authors) list the original receipt, followed by a modern translation. To be honest I haven't tried any of the recipes yet, and I heard about it through my LJ f-list or f'list's f-list. It might be
colleency who mentioned a receipe she tried that sounded delicious.
Anyways, when I went looking for it there weren't any under $5 copies available. Now there are. :/