FOAM Covers A Scotland Beach After Huge Storm. WTH!?

WTF!? So what could of caused this? The explanation in the article does not sound right...
In the article they claim this is normal, yet no one living there has ever seen anything like it before...
This part of Scotland has had many storms. Under the same circumstances, but they have never had this foam before! 
http://www.bbc.co.uk/news/uk-scotland-north-east-orkney-shetland-19716141