Values aren’t everything. Some of us want to handle our coins with care, viewing under different lighting conditions, as nature (or mints) intended, not entombed in scratchable plastic.
I'd say your 1913 is 1+A - the reverse is clearly so, and if you look at GRA:BRITT on the obverse and compare it with the 1915, you'll see there is a bigger space between A:B and the I of BRITT is to a space not a tooth.
Could the LE stand for 'Limited Edition', and the CM for 'Confirmed Mintage'? No idea what the other letters would be unless the final P is 'Production', or even 'Proof' to indicate there is also a proof issue for that coin?
Yes, it's hard to predict, but given that the 'not fully struck up' specimens were not the original intent, there are bound to be a minority that - for some reason or other - ARE as intended. Obviously those are worth a premium.
What many people don't realise is that native British - mistakenly referred to as Celts - traded all around the Mediterranean, I believe as far as Turkey? Maybe even beyond. This didn't stop with the withdrawal of the Romans, and Tintagel may have been one of those defended strongpoints that also acted as a trading port.
Only $10 Bernie.
I remember once doing a big double take when I saw a 1928 penny with a large portrait .. after some investigation I found the same seller was offering a 1927 penny with a small head.