That is what is known as a filled die or die chip, sometimes a small bit of stuff (grease, metal filling can get caught in the die causing the metal to not flow into the die evenly. Fairly common, now as to your other coin with the misformed E in pence, that is interesting, probably not worth much, but I'm no expert on UK coins, so I'll leave the comments to others.
"Buy the Book Before You Buy the Coin" - Aaron R. Feldman - "And read it" - Me 2013! ANA
Life Member #3288 in good standing since 1982 • EAC Member #6202 • 2¢ variety collector.