I was taught that you should never ask a question in a headline because readers will always supply their own answer - probably not the one that was hoped for. Sometimes the intended answer will be known by readers with absolute certainty, however. There was a question of this sort on the cover of the Sunday Times Magazine this week. "Did they do it?" it asked, concerning the parents of Madeleine McCann. One knew, beyond any shadow of doubt, that the conclusion of the article inside was going to be that they did not. It had to be, for an answer in the affirmative would surely have been followed by a speedy visit to the ST's offices by M' Learned Friends.

Some headline questions provoke a "who knows? who cares?" response - like the bizarre one in Monday's Daily Telegraph: "Are worms happy?" It can't be denied, though, that it caught the eye.

And so did a headline in The Times last Thursday: "Did Unity Mitford Have Hitler's Love Child?" The answer again is one that could be delivered with absolute certainty - "No, of course she didn't." Apart from anything else, is it remotely possible that the most written-about man of the 20th century could have hidden such a secret?

The remarkable thing about the six Mitford Gels is that, with all but one of them dead and gone, they still make the headlines. What a weird lot they were was underlined again this year with the publication of The Mitfords - Letters Between Six Sisters, superbly edited by Charlotte Mosley (Fourth Estate, £25).

This was the book I most enjoyed in 2007. I shall probably write about it here soon, but I mention it now while there is still time for it to figure in any present-buying that remains. This column returns on January 4. I wish you all a merry Christmas and a happy New Year.