I decided the solenoid was definitely suspect and, as this a "new to us" car, buying a new starter looked like the most reliable option to reach optimum reliability.
I found it is not as easy to buy a new starter for such a "modern" as it is for our usual old cars as there are various starters available for this engine. The most probable replacement looked very different from the one I took out of the car. It was a great relief that this new starter did work and to celebrate I also treated the car to a new set of spark plugs. Now our "Josephine" starts and performs as smooth as a French limousine should. Vraiment ça marche très bien!