 Upon their arrival in London the family is greeted by the Prime Minister , Tony Blair , whom Homer mistakes for Mr. Bean . They visit London 's tourist attractions , and later meet J. K. Rowling and Ian McKellen . Grampa tries to contact Edwina whilst Bart and Lisa go on a " sugar rush " after discovering the joys of British candy . Homer and Marge rent a Mini Cooper and start to drive around London but get stuck on Hyde Park Corner . After literally driving in circles for hours , Homer decides to break out of it , plows straight through the gates of Buckingham Palace and slams into Queen Elizabeth II 's horse @-@ drawn carriage . 
