If we’re being honest, they had us at Kristin Scott Thomas. Steely of demeanour, Alpine of bone-structure, KST – to give her her full acronym – is box office Haribo for us (probably the sour ones), luring us in whatever the consequences. Which happens to be, in this instance, Sarah’s Key, a film about the rounding up of 13,000 Jews in Paris during the summer of 1942, by the French police, next stop Auschwitz. Cheery stuff, but this abject episode of French history is juxtaposed with KST’s American journalist living in modern-day Paris, who discovers that her husband’s grandparents might have moved into the house of one of the victims of the fateful round-up, the Sarah of our title. Based on the book by Tatiana De Rosnay, people are saying the tome beats the celluloid, but seeing as we haven’t read it we’ll a) have to take their word for it and b) base it on the film itself, which results in a rousing 3 1/2 out of 5 stars, were we to have a star rating system. Or 5 out of 5, were it based on Kristen’s performance alone. Were we to have a star system.