Sir Oliver St John was an English judge and politician who sat in the House of Commons from 1640-53. He supported the Parliamentary cause in the English Civil War.

Ship money was a tax of medieval origin levied intermittently in the Kingdom of England until the middle of the 17th century. Assessed typically on the inhabitants of coastal areas of England, it was one of several taxes that English monarchs could levy by prerogative without the approval of Parliament. The attempt of King Charles I from 1634 onwards to levy ship money during peacetime and extend it to the inland counties of England without parliamentary approval provoked fierce resistance, and was one of the grievances of the English propertied class in the lead-up to the English Civil War.