F.L. Newal cobbled up a sextant from a protractor, a biscuit tin, chewing gum, and a metal signal mirror
Chewing gum ... why was chewing gum in the lifeboat?
I expected biscuit tins in a British WW2 lifeboat (food) and a signal mirror (signaling). Less so the protractor, but the there were charts in the lifeboat - maybe the protractor was with the charts for computing navigation compass bearings.
Chewing gum isn't on any modern "ten essentials" lists I remember.
As a check, I electronically searched the ~500 page, 4 volume 1985 USAF AFR 64-4 Survival Manual
for "gum", and the only reference to chewing gum was that scented chewing gum could reveal your presence to hostiles.
However, my "go-to" quick reference for military survival kits, lists chewing gum in many WW2 survival kits: USAAF E3 kit: 1 stick, USAAF E3A kit: 4 sticks, Navy E3A: 4 sticks, E17: 4 sticks.
The Emergency Parachute Ration tin had gum, and 2 such tins were in the C-1 Emergency Sustenance Vest. Pulling out my manual for that vest, it says (p. 10):
"Four Pieces Chewing Gum
Chewing a piece of gum occasionally will help to relieve thirst. The gum also can be used to patch small holes in rubber rafts, in plastic containers, and for other patching purposes."
... and also to make a sextant!!!
 Breuninger, Michael S., "United States Combat Aircrew Survival Equipment: World War II to the Present, A Reference Guide for Collectors", Schiffer Military History
 Instructions for the use of Emergency Sustenance Vest, Type C-1, Prepared by the Artic-Desert_Tropic Branch HQ, AF Tactical Center.