Who was the 'Caroline' in Radio Caroline?

In the 1960s indie record producer Ronan O’Rahilly found both the BBC and Radio Luxemburg seemingly in thrall to the major labels. It was illegal to broadcast on land without a licence, but O’Rahilly heard about a ship hosting the ‘pirate’ station Voice of America from international waters. Inspired by a photograph in Life magazine, showing President John F. Kennedy’s daughter Caroline playing in the Oval Office, disrupting the day to day business of government, O’Rahilly adapted a boat and launched Radio Caroline on Easter Sunday, 1964.