Herdwicks: What's so special about the Lake District's sheep?

Herdwick sheep are a distinctive feature of the Lake District landscape.

With their grey-streaked coats and white heads, the breed has been dotted around the hilltops for centuries and their survival was helped by the author and illustrator Beatrix Potter.

The BBC spent a day with a Herdwick farmer at Yew Tree Farm, near Coniston, to see what makes the "smiley, teddy bearish" sheep so special.