Bill mentions the "brides in the bath" in talking about murder. The reference is to the infamous British serial killer, George Joseph Smith. He was a bigamist who would woo well-to-do women, marry them, then drown them in the bathtub. Specifically, he would complain to doctors that his new wife was having dizzy spells and headaches to procure sedatives for them, drug their drinks, then recommend they take a warm bath to feel better. The women essentially would pass out in the tub, and, with or without him holding them under the water, they would drown, leaving him all their money. It was a very famous case for decades after Smith was caught and executed in 1915. It's still well-known in forensics as the case that brought to light how criminals will use the same methods (the famous "MO" or modus operandi) over and over again.
Director Edward Dmytryk was in the UK after being blacklisted as part of "The Hollywood Ten" who refused to testify before the House Un-American Activities Committee. He was granted a work permit in the country by the Ministry of Labour as part of a "directors quota" in place to protect film industry jobs in the UK.
Director Edward Dmytryk reveals in his autobiography that Robert Newton tended to be drunk during the scenes in which he had to play.
Phil Brown (Bill) is best known to Star Wars: Episode IV - Eine neue Hoffnung (1977) fans as Luke Skywalker's Uncle Owen.
Superintendent Finsbury is likely named after Sir Bernard Spilsbury, the famous Home Office forensic pathologist who worked with police to incriminate several high-profile murderers in the early twentieth century, including George Joseph Smith of "brides in the bath" fame.