Not because France's longest-serving post-war president and the most famous courtesan had anything direct in common, but because the most memorable image - at least in Britain - of last Thursday's funeral was the discreet shot of Mitterrand's mistress Anne Pingeot and their 20- year-old daughter, Mazarine, standing side by side in silent farewell.
If nothing else, the sight of Danielle Mitterrand, who will one day be buried next to her husband in the little cemetery at Jarnac, bidding adieu at the service of remembrance along with Mme Pingeot, proves what we suspected all along: they do things differently in France.
Imagine a mistress of John Major's being allowed to grieve with dignity in a black hat in Westminster Abbey, accompanied by their only illegitimate child, or Camilla Parker-Bowles in mourning with a little Charles born the wrong side of the blanket. Unlikely? Unthinkable.
It was the Anglo-French Sir James Goldsmith, a renowned believer in the formality of keeping a long-term lover in your life, who said that by marrying your mistress you create a job vacancy. For wealthy and powerful Frenchmen, keeping a mistress is more than a tradition. It is an obligation.
The Catholic tradition, and the vanguard of inheritance and marital laws that are tied to property, make formal divorce more difficult in France. The French solution, which is cheaper, is to keep both wife and mistress. And to respect them.
Besides a long tradition, there is also a structure to these liaisons. And a language. Only the copines d'une nuit are dispensable. In a long- term partnership, a mistress like Anne Pingeot will be known as the maitresse en titre. Among businessmen, she may well be a key figure in the business. Anyone issuing social invitations will make discreet enquiries as to which partner will attend, wife or mistress. There is no stigma attached in being a mistress, nor pity for his cuckolded wife. Even illegitimate children, like Mazarine, whose long nose marks her out unmistakably as Mitterrand's child, are described with the blameless phrase, enfants naturels.
Mitterrand was by no means the first French leader to honour the tradition. One president died in the arms of his mistress. Another created a scandal, only because his paramour was under-age.
When I was a teenager, my French grandmother introduced me to a woman, whom I shall name Jeanine, and her younger lover Nico. Jeanine had settled into French respectability. Her husband, much older than she, kept a mistress in an apartment, where he would visit her in the hour that is known in France as le cinq a sept. At the same time, Jeanine visited her lover, who lived in a bachelor flat not far away. As far as I know, she and her husband never questioned the arrangement.
In France, there is a secondary tradition to that of keeping a mistress. And that is that young men and women are taught to make love - because it is an art the French believe should be taught - by more experienced partners. Older men take young lovers, who marry and take young lovers in a two-step between the sheets. When Jeanine's husband died, as she approached 60, she set up house with Nico. Just before Christmas, I heard that she too had died.
Few French were surprised to see Mme Pingeot at President Mitterrand's funeral. The surprise would have been had she and Mazarine not been there. Most would prefer to believe Mme de Maintenon was looking down. And smiling.