She often stayed at Brown's Hotel in London, & it's said that it inspired her mystery novel "At Bertram's Hotel"
In its tearoom Miss Marple encounters a wartime friend, 
Lady Selina Hazy, .... inspired by Brown's Hotel, in London, where Agatha 
Christie often stayed ... 1965 said, "A.C. is seldom at her best when she goes 
thrillerish on you.