Carruthers is an employee of the British Foreign Office.
Put that way, which is the truth, it sounds as though he might well be an operative tasked with gathering intelligence for his government but it is hardly that at all. He would be the first to stare at you with astonishment should you make such a suggestion, at least until the events of his unintended escapade with Davies took place. After that, it would still not be quite the truth but it would not be so laughable.
By his own descript, Carruthers is "a young man of condition and fashion, who knows the right people, belongs to the right clubs, has a safe, possibly a brilliant, future in the Foreign Office". He would claim, perhaps correctly, that he is terribly overworked but that assertion might also be mild griping just because he was not free to abandon the City of London as his friends had for more pleasant weather and more interesting diversions.
He did not really enjoy the occasional letters from his pals on holiday because from their words he could tell that though they claimed to miss his company, they were enduring his absence with amazing fortitude.
Seeking his own diversion towards the middle of September of that year when finally work allowed him to escape, he is asked by an acquaintance named Davies to join him on his sailing boat for a fun excursion. Carruthers thought this meant a pleasure yacht with other fun-seeking companions to while away the hours. What he got was just what Davies had actually said, a small sailing boat.
Sailing in a small vessel in the North Sea and the Baltic as summer has left and autumn is approaching is not something most would consider a relaxing pasttime and Carruthers definitely did not find it so.
And that is even before he learned the real reason Davies had for sailing into German territory for something far removed from entertainment.