Why did the witch hunts occur in England?

The English witch hunts, and those of the English colonies, mostly happened because King James I of England (James VI of Scotland) was a bit of a nut on the subject, to the point, possibly, of paranoia. When he went to Denmark to meet the princess to whom he was engaged, his ship was hit by a storm, which he blamed on witches. He wrote a book on the subject of witches, their supposedly evil nature, and how to identify them, and the English were very quickly caught up in the whole thing because of royal encouragement.

Earlier laws forbidding witchcraft in England dated back to the reign of King Henry VIII. There had been Anglo saxon laws as well, though they had fallen into disuse during the Middle Ages. These earlier laws were doubtless used to prosecute a few individuals, but were not use as a basis for wide scale witch hunts, in which people were actively sought and examined to see if they were witches, to be subsequently tried and executed.