old man of the sea

Isabella Birdの "Unbeaten Tracks in Japan" を読んでいます。
Ito青年と通訳の契約をして、前金を渡しましたが、Dr. H から彼はもう来ないと言われ、不安です。

Ever since the solemn night when the contract was signed I have felt under an incubus, and since he appeared here yesterday, punctual to the applied hour, I have felt as if I had a veritable "old man of the sea" upon my shoulders. He flies up stairs and along the corridors a noiselessly as a cat, and already knows where I keep all my things.

約束通り青年が現れ良かったですね。　さて、"old man of the sea" はどんな意味でしょうか？
・Collins Dictionary: a burden, annoyance, care, or the like, from which it is extremely difficult to free oneself
・Infopleasey: a burden, annoyance, care, or the like, from which it is extremely difficult to free oneself.

この表現の由来が気になり調べると "Britannica Kids" のサイトに次の説明がありました。
In the story of the fifth voyage of Sinbad the Sailor in the collection Arabian Nights, a character known as the Old Man of the Sea begs Sinbad to carry him across a brook and then refuses to be dislodged from his shoulders. After many days and nights Sinbad finally rids himself of the nuisance by getting him so drunk that he falls off. The term “old man of the sea” has come to stand for a bore or heavy burden, someone who cannot be rid of easily.