"A bowl of corn flour" -- ring a bell? UK readers?

[Kimstu]

Here’s an early 20th-c. (?) book entitled Cookery for Invalids and Others, with the following remarks on arrowroot and cornflour:

Arrowroot. — This is pure starch, and in itself, as a food, of but little value. But from its astringent nature it is very useful in special forms of illness, and is regarded as a good medium for conveying other articles of nutrition, such as eggs, wine, brandy, milk, &c. ; moreover, it is said to prepare the stomach for more solid nourishment later on, and is generally found soothing in irritable conditions of the stomach and intestines. For this reason it should be borne in mind as a thickener for soups, &c. ; although corn flour (Kingsford’s Oswego or Brown and Polson’s) makes an excellent substitute. Store it in a dry place, and see that it is free from lumps before beginning to mix it.

Egg Arrowroot. — Prepare a teacupful of arrowroot as below, and when it is off the boil beat in a fresh egg, which has first been whisked well ; give as it is, or set in a steamer for a minute or two. It may be taken hot, tepid, or cold.

Milk Arrowroot. — Make as water arrowroot below; boil for five minutes at least: cream is sometimes put in to increase the nourishment.

Water Arrowroot. — Allow half an ounce of arrowroot to half a pint of water; mix to a smooth paste with cold water, boil the rest, and add it, stirring well ; then boil for a few minutes, stirring all the time. Add sugar to taste, but sometimes none is allowed. A morsel of cinnamon may be boiled with it and removed ; where disliked, ginger can replace it. Wine or brandy is frequently ordered ; either should be added after boiling. This is the least nourishing of all, except when such additions are made, then it is found to agree better than milk arrowroot in most cases. These are average proportions ; often liked thinner or thicker.

I’m inclined to think that the corn-flour variant of that “water arrowroot” is what Christie was talking about.