The original Chewits advertisements featured the ‘Monster Muncher’, a Godzilla-resembling mascot on the hunt for something chewy to eat.  But the ‘Monster Muncher’ could only be quelled by a pack of Chewits. They used claymation special effects, and also included a voiceover style reminiscent of a 1950s radio serial.

“London’s under siege.
But beware, this gobbling brute is a master of disguise.
‘Ere, matey!’
Do not confront it.
Always carry your regulation Chewits!
There’s nothing chewier.
And keep the enemy from your door.
Chewits.
CHEW for VICTORY!”