Uncharted Island The Onedin Line : Season 4 Episode 6

Baines and Onedin find an uncharted island,rich in guano,which they intend to mine without telling anybody. However,Matt Harvey learns about it and sets sail in a Frazer Line ship but fails to locate the island. Instead he returns with valuable whale-bone and claims that the guano was too acidic for use. Elizabeth believes she has got one over on her brother until she discovers that he already knew this fact.