Appears real to me - known as a clip. It happens when the planchet is punched out of a strip of coin metal and the punch overlaps the edge of the strip. As for value - no idea. Clipped coins in the US attract a lot of interest because there is a large error collector community. But in the UK - the interest is almost negligble. There is some interest here in the US for collectors of UK coinage - but nothing like for US.
