"Winston Churchill during the Second World War" The Prime Minister Winston Churchill's daughter, Mary, cuts into a cake made to celebrate her 21st birthday with a midshipman's dirk on board HMS RENOWN on 15 September 1943. She, along with her mother and father, was returning from the USA and Canada to the United Kingdom. Members of the WRNS, who worked as Cypher officers on the vessel, stand around the table, as does Mary's mother, Clementine, who can be seen on the right.