andy: You are dead right.
In Private Eye Queen Elizabeth II is always referred to as "Brenda", and the Prince of Wales as "Brian". This is a result of the 1969 BBC documentary Royal Family, after which the magazine gave each member of the Royal Family working class nicknames, as though they were characters in a soap opera. The Duke of Edinburgh is "Keith", the late Princess Margaret was "Yvonne", and the late Diana, Princess of Wales was dubbed "Cheryl".