Please help with identifying WWI shell case, diameter 4 in

Good evening ammunition experts.

Could you please help me with identifying this shell case. I believe it is from WWI. I see 1916 number on it, which might be the year of production. I wonder what kind of shell it is, what weapon would use it and also what is the meaning of all those numbers. These shells were made into steam toys. The diameter of each shell is 10 cm or about 4 inches. The length is 12 inches.

Thank you.

18 Pr = 18 Pdr or 18 Pounder, British field gun.

1916 is the year of manufacture.

EWBC is probably E.W. Bliss and Co., apparently a British company with manufacturing both in Britain and the U.S. during WW1 (information based on a discussion on the BOCN forum).

The broad arrow marks indicate British Government acceptance / property.

C signifies the cartridge case was loaded with Cordite.

F signifies a full charge of cordite.

Other markings are hard to read.

Pressure vessel(s) of some kind? Interesting alternative use for artillery cartridge cases.

They are probably home-made boilers for model steam engines. This was apparently fairly common in the UK at least. I have seen a few of these at flea markets. Other collectors here have also mentioned coming across them.

Thank you very much bdgreen for such a great explanation. You must have a lot of experience in this field. Yes, these shells were made into steam boilers and became toys back in the days.