Margery Allingham 
Mr Campion and Others [EPUB ebook] 

The second prettiest girl in Mayfair was thanking Superintendent Stanislaus Oates for the recovery of her diamond bracelet and the ring with the square-cut emerald in it, and Mr Campion, who had accompanied her to the ceremony, was admiring her technique.
She was doing it very charmingly; so charmingly, in fact, that the Superintendent’s depressing little office had taken on an air of garden-party gaiety which it certainly did not possess in the ordinary way, while the Superintendent himself had undergone an even more sensational change.