IN A BRILLIANT ARTICLE, FERDINAND MOUNT RECENTLY drew up a balance sheet of the ‘Thatcher decade’ in which he attempted to discern the laws governing political longevity. Now, when he looks at various politicians who are or were remarkable in their capacity for survival, it is striking that he does not so much as mention the head of a neighbouring country, an almost exact contemporary of Mrs Thatcher, since Franpis Mitterrand has been President of the French Republic since 1981 and should, in principle, remain president until 1995. This no doubt is because, in the eyes of F. Mount, Mitterrand's longevity is of a different nature from that of Mrs Thatcher and is far less politically instructive.