"That would be highly ineffective, since chocolate bars are wrapped in tin foil."
Is it really the 1910's in the UK?
I have not seen a tinfoil wrapped candy bar for over 30 years. plastic wrapped with a Metallica plastic? yes!
I don't know about UK, but here in continental Europe, the good chocolare usually has tin foil, while the cheap chocolate and the chocolate-containing-stuff (you are not allowed to call it chocolate if you do not use chocolate butter but some replacement) use some cheap replacement (often not even metallic to make it clear it is a really super-cheap one).