*Crime, Spies & Sleaze: Tommy and Tuppence were a couple of detectives who starred in five books by Agatha Christie, four novels and one short story collection. They are unique amongst her characters in that they aged in real time, thus they were bright young things in their first outing, The Secret Adversary from 1922 and retired pensioners by their last, Postern Of Fate (1973). Two of those are featured in this update. Featured in many TV and radio adaptations, my personal favourite was the early 1980s series with James Warwick and Francesca Annis in the title roles. 
PICTURED: ALL TOMMY & TUPPENCE BY AGATHA CHRISTIE ALL SOLD
BY THE PRICKING OF MY THUMBS Fontana 1971 1st UK PB thus GD £3
POSTERN OF FATE Fontana 1976 1st UK PB GD £3
THE SECRET ADVERSARY Pan 1974 21st UK PB GD £3