Sid Towers's murder aboard the narrowboat

Sid Towers’s murder aboard the narrowboat transforms a death discovered after a meeting into the central locked-room problem of Peter Diamond’s investigation. Sid is found in Milo Motion’s boat, yet Milo was at the police station reporting the missing stamp, and the boat’s security appears to rule out an ordinary entry. The case therefore rests on a sharp distinction between what the hardware can establish and whether the people involved have told the truth.

Discovery and immediate reactions

The news reaches Shirley-Ann Miller by local radio at eleven. When Polly Wycherley tells her what has happened, she is deeply shocked; the account is difficult to absorb precisely because Sid had seemed inoffensive. Polly says that he was found on Milo’s narrowboat the night before, after the Bloodhounds’ meeting. The revelation shifts the gathering’s aftermath abruptly from club business to a murder investigation.

Polly immediately stresses that Milo could not have been responsible: he was at the police station telling officers about the missing stamp. Her distress is visible as she searches her handbag for a tissue, blows her nose, and trembles. Shirley-Ann’s response is disbelief and grief, while Polly admits that she is as puzzled as her friend and that the police are withholding information. Their conversation establishes both the shock surrounding Sid’s death and the early importance of Milo’s whereabouts. His police-station visit is offered as an alibi, not presented as a final solution to the crime.

The boat and the search for a weapon

Later the same afternoon, Peter Diamond drives Milo back to the Dundas Boatyard so that he can collect a change of clothes from the boat. The Scenes of Crime team has finished its work. Police attention has narrowed to a pair of divers searching the canal bottom for the murder weapon, although the shallow water makes the operation more like wading and bending double than diving. After three hours of scavenging along fifty yards on either side of the narrowboat, they have assembled a disparate haul on a blue tarpaulin: a horseshoe, two plastic milk crates, a bicycle pump, a birdcage, about twenty beer cans, and pieces of stone. None is identified as the weapon.

Diamond calls off the search for the day. He considers the chance of finding the weapon there slim, reasoning that a killer capable of the apparent deception would be unlikely to dispose of it in such an obvious place; nevertheless, the search has been required as a matter of procedure. He asks Milo to consider whether anything aboard the boat is missing that might have been used to strike Sid over the head. Milo cannot think of anything immediately, but says that he will look. The question keeps the inquiry anchored in practical evidence even as the circumstances of entry begin to resemble a puzzle in detective fiction.

Security and the apparent locked room

The stern door has a fresh lock, so a constable must open the boat for Diamond and Milo. Milo’s German-made padlock has already been dismantled and examined at the forensic laboratory. The mechanism shows no flaw and no sign of tampering; it is a high-security close-shackle lock with more than six million key variations. The manufacturer’s claim, as reported to Diamond, is that each padlock sold in Britain has a unique key pattern. Forensic examination thus gives the lock an unusually strong appearance of reliability, but it cannot by itself establish who used a key or whether Milo’s account is true.

Diamond has repeatedly considered the narrowboat and its security without discovering how Sid’s body could have been put inside. He can reduce the apparent contradiction to a sequence of conditions: Milo says he locked the boat when he left; he says the key remained on his person; the keys fitted that padlock and no other, with no second key; and the only other entrance to the cabin, at the fore end, was bolted from inside. When Milo returned with John Wigfull, the padlock was still in place. Milo opened it with his key, and the men discovered Sid’s corpse in the cabin.

These details give the event its closed-room structure. The lock is not found broken or visibly interfered with; the key is not said to have been left behind; and the alternative door is described as secured from within. Yet those conditions depend in crucial part on Milo’s statements. Diamond returns repeatedly to the qualification that the account holds only if Motion has spoken the truth. The apparent certainty of the hardware therefore sharpens, rather than settles, the question of human reliability.

Investigative significance

For Diamond, Sid’s murder becomes his own locked-room mystery, a Gordian knot that resists resolution even after repeated mental review and another inspection of the boat. The scene has been processed, the weapon search has begun and been suspended, the lock has been tested, and the route into the cabin has been narrowed to a small set of stated conditions. None of this yet explains how the body came to be there.

The murder’s immediate significance lies in the collision between a seemingly secure physical arrangement and an account that must still be tested. Milo’s presence at the police station makes him appear to have an alibi for the time associated with the discovery, while his key and the lock place him at the center of the boat’s access problem. Diamond does not treat either circumstance as conclusive. The event leaves the investigation suspended between a mechanical impossibility and the possibility that some human assurance, rather than the lock itself, is misleading.