PS: The claim by Shanks, quoted in TZ for America/Fort_Nelson, that most of BC did not have DST in 1946 is correct.

Rule    Vanc    1946    only    -       Oct     13      2:00    0       S

should be

Rule    Vanc    1946    only    -       Sep     29      0:00    0       S

According to Victoria Daily Times, Saturday 28 September 1946.

Many parts of the state went back to standard time earlier in September, according to this article.