The online salon talk this week has been whether award-winning ITV drama Downton Abbey requires a mezuzah.

Leading character Lady Cora (below) has already been revealed to be the daughter of Cincinnati millionaire Isidore Levinson.

Later this year you will be able to learn about her matrilineal line when her mum - played by Shirley MacLaine - turns up in the next series. Keep your eyes peeled for tell-tale signs: lox and bagels beside the devilled kidneys or a JNF tin in the drawing room.

Jonathan Sarna, professor of American Jewry, reckons it plausible that a Cincinnati Jew at the time would have married in.

But one historian unlikely to care a fig about a Jewish countess is Simon Schama, perturbed at the popularity of a show he dismisses as "a steaming, silvery tureen of snobbery".