This is the centenary year for Georgette Heyer's 'The Black Moth', written when the author was 17 to amuse her convalescent brother, she kept on writing until 'A Lady of Quality' came out in 1972, with 'My Lord John' published in 1975 the year after she died.
Those changes of attitude are also reflected in the covers her books get, even more so since her death, and publishers were presumably completely free to go with whatever they liked, or thought would do. The most obvious change is in what the expectations of romance and specifically historical romance as a sub-genre have come to be.
I don't think of Heyer as a romance writer in the Barbara Cartland sense (I wonder how well known Barbara Cartland is these days, I see her books are still available) although Cartland plagiarised Heyer's work, or in the Julia Quinn sense - although the success of the adaptation of Bridgerton is surely bringing new readers to Heyer (they'll find a lot more humour and a lot less sex). She's more in the Robert Louis Stevenson mold - somewhere between the high drama of 'The Master of Ballantrae and the comedy of The Wrong Box. She definitely has plenty in common with Baroness Orczy of The Scarlet Pimpernel fame and leans heavily in her early novels on the writers who would have been popular (even racy) in her youth.
In Heyer the romance is only one element, adventure, mystery, comedy, and often a love of historical detail, all get more or less equal weighting throughout her books and the early covers represent this with a steady shift as the years pass to something more gendered and borrow in its expectations.
My own collection of Heyer's were bought in the late 1980s, they're Pan editions, the cover design is fairly horrible, and I have a real sentimental attachment to them. I really love the incredibly lurid Pan covers that preceded them (fabulous) and would be tempted to collect these along with the first edition hardbacks if I had space and money to make it feasible. The Pan covers may be high camp and pulpy but they capture the adventure element, the hardback editions are a decent indication of the comedy of manners you'll find within.
The more recent covers have mostly been uninspired. The detective novels have done okay, and I really quite like the ones that have appeared regularly around Christmas in the last few years, but stock images of Victorian art are dull and tell me nothing about what's going on in the book. The newest jackets which I think are on about half a dozen titles match the covers the Bridgerton series has, and again say nothing about the books themselves. It'll be interesting to see what The Folio Society does with 'Venetia' later this year (but their editions always look good) but the one that's really caught my attention is the hardback to celebrate the centenary of The Black Moth.
This is a beautiful book, the cover is the colour of mulberry juice (I realised after covering myself in mulberry juice). It's robust but light, has a glorious mustard/gold ribbon - the colours are worthy of some of the costumes Heyer describes, no dust cover to get damaged, an exemplary introduction and afterwords, print friendly to middle-aged eyesight, and a highwayman motif that does justice to the story and its spirit. There's even a handy list at the front which breaks down the books into categories - I'm struggling to find praise high enough for this edition.
What I will say is that if all 33 of the Georgian and Regency novels appeared like this, each with a bespoke introduction (or even just the Philippa Gregory one here) I would find the £428.67 to buy them all (at £12.99 each) it would be worth it and then some.