Jane Austen was having fun with it at the beginning of Northanger Abbey (which I am convinced was half rewritten late in her life, at the height of her powers,, but she abandoned it halfway through. I think you can almost peg the paragraph where she stopped the rewrite and left the early version) but I digress.

We even get a glimpse of male idiom in John Thorpe--which matches with a lot of printed matter of the period. But Isabella Thorpe is a delicious example of female idiom. Most of it is exaggeration, but the phrases of it, the way it's used, was very much female language. And it's there in so many period publications, letters, etc. But Austen exaggerated slightly for effect.

If you read a lot of period material and then go back to Heyer, you discover that she had gradually reshaped the Regency characters' language at the substrate: most of her heroines are Bright Young Things in period dress. Austen's female characters don't use male idiom. They use their own. Heyer's admire mannishness and borrow freely from masculine idiom and custom, but within their class and style, just like Bright Youmg Things. And her male characters find that hot, just as Heyer's contemporaries did.