Open Country: Fair Isle

Halfway between Orkney and Shetland, Fair Isle is one of Britain's most isolated inhabited islands. It's famous for knitting and birds, and those still form the basis of the island's economy. Exhausted migratory birds blown off course regularly add to a long list of unusual species recorded by the local bird observatory. Martha Kearney joins the island's Head of Ornithology, Alex Penn, to ring some visitors and sit for a while with Britain's friendliest colonies of puffin