You do require a firearms (shotgun) certificate however to own one of these, but they're quite easy to aquire after the appropriate police checks.
Thay actually fall under the catagory of shotguns as per the 1988 Act
http://www.opsi.gov.uk/acts/acts1988...en_2.htm#mdiv1
EL
"I've oft been told by learned friars
That wishing and the crime were one
And heaven punishes desires
As much as if the deed were done.
If wishing damns us, you and I
Are damned to all our hearts content.
Come then we may at least enjoy
Some pleasure for our punishment..."
Sir Thomas More