Most solicitors are not generally known to the public; Crocker is an exception. Much of his work has been connected with insurance, particularly suspicious insurance claims, and on two notable occasions he achieved (what was to him unenviable and unsought) fame.

The first occasion was the famous case of Sidney Fox who, in 1929, was found guilty of the murder of his mother at Margate. Crocker was the man behind the insurance investigations which took Fox to the scaffold. Crocker's activities on behalf of the insurance community (he was closely connected with Lloyd's) became a matter of public attention. His most famous and, publicly, most widely known investigation was into the Fire Raisers Case of 1933. Cracker's painstaking enquiry was instrumental in bringing the arson gang to justice.

The Director of Public Prosecutions made Crocker his Agent-no London solicitor in private practice had ever before been appointed to act for the Crown in this way. The subsequent trial at the Old Bailey lasted 33 days; Crocker was himself provided with an office there and at one point he carried a small automatic pistol among the loose change in his trousers' pocket (an unusual, and, as it turned out, unnecessary weapon for a solicitor!).

Sir William's book is full of fascinating stories of investigation. As Sir William himself writes: 'My interest was for the most part limited to those claims in which there was a smell of fraud but proof of it was hard to come by.' There is the curious story of the famous wigmaker Willie Clarkson's forged will; the story of the Budget leak of 1936 when J. H. Thomas was politically discredited by the findings of a Tribunal of Enquiry on which Crocker acted as solicitor for Lloyd's Committee; a fascinating account of the Shoreditch murders and the Sidney Street Siege, and, for good measure, the 'Marie Celeste' sea mystery solved at last.