When Blair left the Titanic on 9 April 1912 he took with him the key to the Crow's nest locker, presumably by accident. This is believed to be a reason why there were no binoculars available with the crew during the voyage. According to other versions, the binoculars were not in the locker, but were left behind in his cabin, or he took them along with him when he left the ship, as they were his personal set of binoculars. The absence of binoculars being a factor in the sinking of the Titanic, became a point of investigation in the subsequent inquiries into the sinking.
The lookouts at the time of the collision, Frederick Fleet and Reginald Lee, maintained during the inquiries that they were informed they were to have no binoculars during the voyage. Fleet, when asked by a commission of inquiry composed of members of the United States Congress whether or not they would have seen the iceberg from farther away, replied that he would have seen it "a bit sooner". When asked "How much sooner?", he responded: "Well, enough to get out of the way." According to legal expert Gary Slapper, though, Blair's "forgetfulness wasn’t a material reason for the disaster" as there were other intervening causes.
The key itself survived and was donated by Blair's daughter to the International Sailors Society. On 22 September 2007, it was sold in a group of items including a postcard Blair wrote on board the Titanic via an auction held by Henry Aldridge, including a ticket from Belfast that fetched £32,000 and a postcard sent by a passenger which sold for £17,000. The key was purchased by Shen Dongjun, the CEO of jewelry retailer TESIRO's Chinese division for £90,000, and is currently on display in Nanjing.
The auctioneers said about the importance of the key that, it was a conjecture that the key could have saved the Titanic had it not left the ship. They also said that the money from the auction of the key will be used to set up bursaries and scholarships in Blair's name.