Frances Williams Wynn reveals something of herself ..

... while also talking about the great figures of her day.

She's writing about her first recollections of William Pitt the Younger, Charles James Fox and the Duke of Wellington.

But all of these pale before the man who seems to have been her first crush, Mr Windham. (Anyone know who he was?)

In my recollection, no person appears to have possessed the power of making conversation delightful as much as Mr. Windham. His peculiar charm seems to me to have been that sort of gay openness which I should call the very reverse of what the French term morgue.
To all, this must be agreeable, and it is peculiarly delightful to a young person who is conscious of her own inferiority to the person who condescends to put her perfectly at ease. During the party at Stowe to which I have alluded, I found myself embarked for the morning's or rather day's amusement, in a carriage with Lady King, Lord Braybrooke, and Mr. Windham. My mother was in some other carriage, my two sisters in a third.
When we all met in our own rooms, they with one accord voted they were a little tired and very much bored. I, though much more liable to both these complaints than any of the party, could only say I had been highly amused the whole day.
The fact was, they had no Mr. Windham to listen to, and I had; and yet, truth to say, when I was asked how he had contrived to amuse me so much, I had very little to tell even then; and now after so many years that little has passed away.

UPDATE 21/11: I think I've worked out who this is, or at least most likely is: William Windham, (1750–1810). The ONDB says of him:

"Acknowledged as one of the gifted young men of his generation, he numbered Edmund Burke, Charles James Fox, and Samuel Johnson among his particular friends, and was a pallbearer at Johnson's funeral. Windham vacillated between love of academic study and the duties of a public career. He was a talented linguist and wrote three mathematical treatises, albeit unpublished ones.
As late as 1790 he described himself as ‘a little of two characters and good in neither: a politician among scholars and a scholar among politicians’ (Windham Papers, 1.96). Deeply introspective and prone to bouts of indecision, Windham was nevertheless a popular figure in polite society. Wraxall deemed him ‘graceful, elegant and distinguished’ with conversation that displayed ‘the treasures of a highly cultivated understanding’ (Historical and Posthumous Memoirs, 4.73). A bachelor until his late forties, he married, on 10 July 1798, Cecilia (1750–1824), daughter of Commodore Arthur Forrest (d. 1770), and his wife, Juliana; they had no children."