Milo's lost keys

Milo's lost keys turn a remembered mishap into physical evidence, overturning the assumption that the padlock aboard the Mrs. Hudson had been changed. Their recovery from the canal allows Peter Diamond to test the keys against the lock associated with Sid Towers's death; when one opens it, John Wigfull's theory of a substitution no longer holds.

The keys and their loss

The keys first matter because of the apparent problem of access. Diamond points out that no door or window showed signs of interference, while Milo Motion insists that his key is the only one in existence. Diamond reminds him of the spare key he had dropped in the canal. Milo accepts the correction, then places the loss toward the end of the summer, probably in September. His account supplies circumstances that make the forgotten spare a concrete possibility rather than an abstract exception.

Milo had lost his car keys at the same time, and confirms that the keys were together on a ring. The incident happened after dark, following an evening at the Cross Guns in Avoncliff. He had moored his boat above the pub, on the stretch of canal before the Avoncliff Aqueduct, and treated himself to a meal and several beers. He says it was unusual for him to drink to excess. Returning alone, he opened the boat and stumbled while pulling the door open; the keys slipped from his hand and over the side. He had spares for all the keys, so he did not regard the loss as immediately disastrous.

The next morning, Milo did not attempt to retrieve them. He believed they would have sunk into the mud and that recovery was hopeless. That decision left the keys below the canal surface, beyond his ordinary reach, and their absence later became entangled with the question of who could open the boat. The mundane sequence—an evening out, an unsteady return, a dropped ring—would acquire a different importance once the locks were examined.

Recovery from the canal

The lost keys return to the investigation when divers get in touch after completing the recovery job. Diamond brings a rusty bunch of keys out of his desk drawer and identifies them as the keys Milo dropped in the canal. Julie Hargreaves immediately recognizes what the find establishes: Milo had told the truth about where he lost them. The recovered object gives the investigation more than confirmation of his account; it makes a direct test possible.

Diamond takes a padlock from the same drawer, identifying it as the one on the door of the Mrs. Hudson on the evening Sid Towers was found dead. He selects a key from the recovered bunch and inserts it into the lock. Rust falls onto the desk as he turns the key, and the shackle springs open. The test links Milo's recovered keys to the particular padlock under investigation. The rusty residue and the lock's movement are visible results, not deductions resting solely on recollection.

What the test changes

The lock opening overturns the substitution theory attributed to John Wigfull. According to that theory, Sid Towers had fitted a new padlock to the boat; but if one of Milo's original keys opens the lock that was there on the night Sid was found dead, Diamond concludes that it must be the original padlock. He and Julie recognize that they had been working from a false assumption. The discovery therefore changes the status of the supposed locked-room puzzle: the lock no longer supports Wigfull's account of a newly fitted padlock.

The evidence is specific but bounded. It establishes that the recovered keys include one that opens the relevant padlock, and it confirms the location Milo gave for losing the bunch. It does not, by itself, explain every circumstance surrounding the lock or Sid's death. Its decisive force lies in disproving the substitution premise on which Wigfull's explanation depended. A keyring once dismissed as irretrievably lost becomes the instrument that exposes the weakness in the investigation's working theory.

Narrative significance

Milo's lost keys move through three distinct roles: an embarrassing personal mishap, a possible answer to how a locked boat could be opened, and finally a physical check on the detectives' assumptions. The shift depends on recovery. While the keys remain beneath the canal mud, Milo's account can be treated as a detail from the past; once the divers return them, Diamond can place one against the actual padlock and let the mechanism answer.

The episode also distinguishes a plausible theory from a tested one. Wigfull's account had supplied an explanation for the lock, but the recovered keys and the opening shackle force Diamond and Julie to abandon its central premise. The keys do not solve every part of the case on their own. They do something narrower and essential: confirm Milo's account, connect his lost bunch to the lock, and make the investigators revise what they thought had happened aboard the Mrs. Hudson.