Four of the five Britons killed during a whale watching trip in Canada on Sunday have been named. <br />Among them were a father and son who'd been on holiday on Vancouver island. <br />The Leviathan II sank so quickly off the coast of western Canada that there was no opportunity to send a Mayday call, its operator has said. <br />A sixth person who is missing is Australian, the country's Department of Foreign Affairs and Trade confirmed.
