Originally Posted by CyrilVladisla
There was an Edith Katherine Selby-Bigge Bowes-Lyon (1889-1971). She was the wife of Captain Geoffrey Bowes-Lyon.
Newspapers referred to her as Mrs. Katherine
Bowes-Lyon, so I think you found the right person. In the 1950s she ran a coffee lounge in Mayfair where she also sold butter and cream from her son-in-law's farm.