Sarah Knight . chelsea /marylebone 1794

[frederickay]

Hi , i am looking for any reference to Sarah Knightof & Church st , Queens elm , born out of county ,in 1770 ish.
She is living in the Spanish Embassy as the mistress of Don Carlos De irujo and has his child Lavinia in 1794 and dies in Brompton . 6 blizard place 1841 .
In letters she is referred to as a servant .
She was or ginally buried at St Luke's  Chelsea but her name is on a stone in Brompton cemetery.
names in letters about her , but unknown to me  are thomas ,husband of Lady  Lan? and Ian king .Charles Bricknell (lawyer ) and Sir Herbert Taylor . Is anyone out there looking in anyone  of these circles .
thanks frederickay