Robert Cecil, Earl of Salisbury was a right "beardface" whilst Prime Minister. His final term ended in July 1902. After then, a clipped little moustache became fashionable for Prime Ministers then clean shaven during and after World War II with the exception of Anthony Eden and Alex Douglas Home. Mrs Thatcher was the only British Prime Minister completely unable to grow a beard. It can be argued that Pitt the Younger could only grow bumfluff being just 24 but a full growth on the end of his chin did manifest itself several years later.