Is he or isn’t he? A topic that has dominated conversation at myriad dinner parties – those that I attend, at any rate – forms the basis of a whole book, most entertainingly written by Michael Bloch and published by LittleBrown.

Receiving my copy a few days ago I was pleased to see, emblazoned on its back cover, my words of praise from a review earlier this year of Bloch’s biography of Jeremy Thorpe. I was in a distinguished band of fellow critics including Craig Brown, Philip Hensher and Daniel Finkelstein.

Bloch’s theme this time is politicians of the past and present who clearly were/are gay or who could be presumed to have been so.

Thorpe himself, of course, naturally figures in the list, though he was judged not to have been homosexual in the court case concerning his attempt to silence the male model Norman Scott, who claimed a gay affair with him.

That his trial ended as it did meant that Bloch had to wait until the politician’s death before publishing his biography, though it had been completed years before.

His list of ‘closets’ is a long one and contains, as we shall see, some surprising names.

So many supposedly gay Tories are identified that one almost raises an eyebrow when reading, on page 214: “It seems unlikely that Sir Alec Douglas Home (formerly 14th Earl of Home), who was Prime Minister between the autumns of 1963 and 1964, had homosexual leanings.

“However. in July 1965 Douglas-Home was succeeded as Conservative leader by the unmarried Edward Heath.”

But despite that ‘however’, Bloch reaches the remarkable conclusion that the Incredible Sulk was, in fact, not gay.

“If Heath avoided all intimacy with women, he never showed much desire for intimacy with men either. Even at Oxford he steered clear of the close platonic relationships which were common among the male undergraduates.”

Bloch sums up: “At the outset of his career he seems to have concluded that, if he was to realise his ambitions (particularly coming from the background that he did), any homosexual feelings would have to be vigorously suppressed; and he stuck to this policy for the rest of his life.”

Bloch made his literary name with a number of books about the Duke and Duchess of Windsor, having worked for their formidable Paris lawyer, Maitre Suzanne Blum.

Later he was befriended by the gay buildings expert and diarist James Lees-Milne, only discovering, as he set about the editing of his later diaries, how besotted with him the writer had been. Bloch eventually wrote an excellent biography of him.

Lees-Milne knew everybody of his day, and everything about them. Clearly, there would have been much discussion with Bloch about who was gay, which no doubt explains why Lees-Milne’s name crops up so regularly in Closet Queens.

Was it he, perhaps, who first steered Bloch in the surprising direction of finding that Winston Churchill was a closet, emotionally if not physically.

Bloch writes: “There is no shortage of examples of Churchill taking a fancy to young men.”

Among these was the cavalry officer Archibald Sinclair, whom he offered to launch on a political career, “though Sinclair’s looks were not matched by much in the way of brains”.

As one who found himself on the wrong side of the broadcaster Sandi Toksvig for suggesting that an over-fondness for mother is a pretty good guide to a person’s sexuality, I could not help noting how so often Bloch applies this yardstick.

An interest in interior design is judged a little suspicious, too.

Of Lord Curzon, for instance, we are told, he “loved old buildings and interior decoration”.

Grocer Heath, “having never previously concerned himself with interior decoration”, threw himself eagerly from 1985 in doing up his new house in the cathedral close at Salisbury.

Though Bloch himself and Matthew Parris, who supplies a foreword, try to suggest a serious purpose to the book, it is, in fact, no more than an enjoyable opportunity to pick up juicy gossip. Read in this way, it provides a diverting few hours.