Not That Sort Of Girl by Mary Wesley.
Rose Peel has made a good, sensible marriage to Ned, a man with money, land, prospects, all that sort of stuff. Only one small cloud on the horizon, really: she doesn't love him. Instead, she is in love with Mylo Cooper, whom she met when he was doing some French tutoring for the sons of some neighbours. This is the 1930s, so Mylo's below-stairs (and possibly slightly foreign) social status and modest financial prospects are a problem big enough to scotch any possibility of them marrying, so good old reliable Ned it is.
Ned is basically a decent man, but he and Rose don't exactly strike up sparks in the bedroom department, if you know what I mean. Partly this may be because Ned is unwilling to give up his habit of occasionally knobbing Emily Thornby, the female half of the oddball pair of twins who live next door to Slepe, Ned's family pile.
So Mylo and Rose are reduced to the occasional clandestine meeting here and there in stolen moments and frantic coupling in various seedy hotels - it being necessary to conceal the affair not just from Ned, but also from Emily and Nicholas Thornby, who would use the knowledge for mischief. As if life weren't complicated enough, not only do both Rose and Emily find that they are pregnant (Rose definitely by Ned, and possibly Emily too), but World War II breaks out. Mylo's fluent French makes him an ideal go-between for helping to spirit French Resistance types back from occupied France, but it's dangerous work, and Rose never knows whether she'll ever see him again.
Eventually the war ends and it transpires that Mylo has survived. Things return to normal, though Rose and Mylo's opportunities to meet are even more infrequent than before, partly because Mylo has married Victoria, a woman from the government department that made use of his services during the war. But they continue to meet on into middle age, until eventually the inevitable happens and Ned dies. Rose is left to reflect on her life, and to wonder what happens now.
The review of The Gate Of Angels listed some 20th-century female authors who'd been late starters, including its own author Penelope Fitzgerald, who'd had her first novel published at the age of 61. Well, we have a new leader in that category, since Mary Wesley was 71 when her first novel Jumping The Queue was published in 1983. It's not entirely clear from her obituary what she spent the previous 71 years doing, apart from doing some intelligence work during the war and embarking on one unhappy marriage and one very happy one. It sounds like a lot of Not That Sort Of Girl (and indeed most of her output, since a lot of the themes seem to be repeated) is based on her life experiences.
It wouldn't be completely ridiculous to group Mary Wesley in with the list in that other book review comprising Penelope Fitzgerald, Penelope Lively, Muriel Spark, Beryl Bainbridge and Alice Thomas Ellis - formidable ladies of a certain age (at the time of writing, most of them are dead now) writing books that appear fairly cosy and orthodox on the surface but which are just a little bit more waspish and subversive than they appear to be. On one level Not That Sort Of Girl is a fairly bog-standard story of long-thwarted love finally freed to express itself, but under the surface there is some sharp satire of the ridiculousness of 1930s ideas of class and morality, and the dreadful bind an intelligent independently-minded woman with a healthy liking for sex could find herself in. The sort-of-joke with the book's title is that Rose actually is that sort of girl, she's just not that sort of girl, you know, the other sort.
There's also something a bit darker going on with the Thornby siblings - it's made as clear as it can be without being explicit that we're meant to infer that Nicholas is the father of Emily's daughter Laura (and it's made clear in the later book Second Fiddle that this inference would be correct). So Not That Sort Of Girl chalks up another entry for the incest list which also features The War Zone, Clea, Invisible, Notice and The Girl With The Dragon Tattoo.
It's not especially groundbreaking, and not that much actually happens, but I enjoyed it very much. It's very sprightly and zesty for a book written by a 75-year-old, and there's some relish about Wesley (evidently a game old girl) writing with gusto about sex and occasionally swearing like a docker.
There is also a lengthy section featuring World War II; the complete list of books in this list featuring that as a theme is too long to reproduce - and in any case I can't be arsed to do the research - but recent-ish entries include Turbulence, Free Fall and The History of Love.
There's a suspicion that Wesley is one of those authors where you don't need to read the whole oeuvre, since all the books cover a narrow-ish range of themes. The book for which she's most famous is probably The Camomile Lawn - which, just to prove the point, features country-house types, World War II and some shagging - which was adapted into a TV series in 1992 featuring the lovely Jennifer Ehle, the lovely Tara Fitzgerald and some splendid nudity. Tara Fitzgerald also appeared in the 1995 adaptation of another Wesley novel, The Vacillations Of Poppy Carew.