Well I thought you meant "Dill" cream, but after further digging, I think that Gill might be some sort of measurement. I've never heard this before. But "1 gill cream" is called for in savory and sweet sauces and cakes, etc. It looks that it might be Australian. maybe some friends from across the pond can verify?
Hey your right on 1 count, It's an Australian term and from your article it sure looks like a term of measurement however in an old Aussie Cook Book, Australian Womens Weekly - called Cookery in Colour,Editor Leila Howrad, circa 1960 it refers often to 1/2 Cup or 1 Cup of Gill Cream. Guess I'm still stumped
After using Google, metacrawler and dogpile and reading a lot of answers, I want to offer this opinion. A gill is the unit of measure above. When the recipe says 1 gill cream. I believe that it is saying 1 gill of cream.