For one thing , she would not have Elizabeth ' s longevity . Between the 1980 s and her death in 2002 , she had several health problems that she probably wouldn ' t have if she hadn ' t taken up smoking as a teenager . As a monarch , I wouldn ' t expect to see her involved in the governance of the realm , but her sister has done an exceedingly good job as a figurehead . I ' m not sure Margaret would have done as well in that role given her illadvised relations with men in her private life . Her first choice was a divorced man with two children , and when that fell through , she married considerably beneath her station . She also probably had an affair within a decade , though she did bear two children with her husband whom she divorced in 1978 . In any case , the future of the monarchy largely depends on who she marries almost certainly not the one she did historically and whether the union produces any offspring . Given that the queen would receive greater scrutiny than the queen ' s sister , she would either have to remain faithful or deal with a scandal . This would mean no Prince Charles , and Diana might still be alive , though not as a princess , and certainly not as Prince William and Prince Harry ' s mother .