It's made from a shell casing.....Sometimes referred to as "Trench Art"! Trech art was a cottage industry, done by civilians during and after WWI (Making souvenirs for the GI to bring home), and since then GIs have been doing it and still do it.
During GWOT we had a few guys making beer mugs out of 105 mm casings and shot glasses from 40 mm casings, and we had a pilot make a bell from a 105 mm casing. We GIs get bored and do things like this to keep busy and have a reminder/souvenir from our time in the war zones.
Boring history lesson over with now.....As for your bell.
Broad Arrow: British mark used to mark Government Property, Ministry Of Defense Supply mark.
Lot 63: Lot number of the ammunition.
CF: Charge loaded with cordite (full charge).
207: Could be an Inspectors mark?
K: Manufactured by Kynoch Factories, Imperial Chemical Industries Ltd., Birmingham, England.
Don't know if there is anything stamped in the 12 o'clock position of the first picture. So far based on the lack of a visible year stamp, it MIGHT (Not 100% sure) post date WWI and possibly WWII. Any other markings will help narrow it down some, also a measurement of the shell diameter might help some.
https://www.worthpoint.com/worthopedia/ww1-trench-art-brass-shell-bell-424734584